Semiconductor Light Emitting Device

ABSTRACT

The present disclosure relates to a semiconductor light emitting device, comprising: a plurality of semiconductor layers, including a first semiconductor layer having a first conductivity, a second semiconductor layer having a second conductivity different from the first conductivity, and an active layer interposed between the first semiconductor layer and the second semiconductor layer, generating light via electron-hole recombination; a first electrode, supplying either electrons or holes to the plurality of semiconductor layers; a second electrode, supplying, to the plurality of semiconductor layers, electrons if the holes are supplied by the first electrode, or holes if the electrons are supplied by the first electrode; a non-conductive distributed bragg reflector coupled to the plurality of semiconductor layers, reflecting the light from the active layer; and a first light-transmitting film coupled to the distributed bragg reflector from a side opposite to the plurality of semiconductor layers with respect to the non-conductive distributed bragg reflector, with the first light-transmitting film having a refractive index lower than an effective refractive index of the distributed bragg reflector.

FIELD

The present disclosure relates generally to a semiconductor lightemitting device, and more particularly to a semiconductor light emittingdevice having a light reflecting face.

Within the context herein, the term “semiconductor light emittingdevice” refers to a semiconductor optical device which generates lightvia electron-hole recombination, and one example is a group III-nitridesemiconductor light emitting device. The group III-nitride semiconductorconsists of a compound containing Al_((x))Ga_((y))In_((1-x-y))N(wherein, 0≦x≦1, 0≦y≦1, 0≦x+y≦1). Another example thereof is aGaAs-based semiconductor light emitting device used for red lightemission.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

FIG. 1 is a view illustrating an example of the semiconductor lightemitting device proposed in U.S. Pat. No. 7,262,436. The semiconductorlight emitting device includes a substrate 100, an n-type semiconductorlayer 300 grown on the substrate 100, an active layer 400 grown on then-type semiconductor layer 300, a p-type semiconductor layer 500 grownon the active layer 400, electrodes 901, 902 and 903 formed on thep-type semiconductor layer 500, while serving as reflective films, andan n-side bonding pad 800 formed on the n-type semiconductor layer 300which has been etched and exposed. The n-type semiconductor layer 300and the p-type semiconductor layer 500 can be of opposite conductivetypes. Preferably, a buffer layer (not shown) is provided between thesubstrate 100 and the n-type semiconductor layer 300. A chip having thisstructure, i.e., where all the electrodes 901, 902 and 903 and then-side bonding pad 800 are formed on the opposite side of the substrate100, with the electrodes 901, 902 and 903 serving as reflective films,is called a flip-chip. The electrodes 901, 902 and 903 are made up of anelectrode 901 (e.g., Ag) with a high reflectance, an electrode 903(e.g., Au) for bonding, and an electrode 902 (e.g., Ni) for preventingdiffusion between materials of the electrode 901 and materials of theelectrode 903. While this metal reflective film structure has a highreflectance and is advantageous for current spreading, it has a drawbackthat the metal absorbs light.

FIG. 2 is a view illustrating an example of the semiconductor lightemitting device proposed in JP Pub. No. 2006-120913. The semiconductorlight emitting device includes a substrate 100, a buffer layer grown onthe substrate 100, an n-type semiconductor layer 300 grown on the bufferlayer 200, an active layer 400 grown on the n-type semiconductor layer300, a p-type semiconductor layer 500 grown on the active layer 400, alight-transmitting conductive film 600 with a current spreading functionformed on the p-type semiconductor layer 500, a p-side bonding pad 700formed on the light-transmitting conductive film 600, and an n-sidebonding pad 800 formed on the n-type semiconductor layer 300 which hasbeen etched and exposed. Further, a DBR (Distributed Bragg Reflector)900 and a metal reflective film 904 are provided on thelight-transmitting conductive film 600. While this structure reduceslight absorption by the metal reflective film 904, it has a drawbackthat current spreading is relatively poor, compared with the use of theelectrodes 901, 902 and 903.

FIG. 12 is a view illustrating an example of the semiconductor lightemitting device proposed in JP Pub. No. 2009-164423. In thesemiconductor light emitting device, a DBR 900 and a metal reflectivefilm 904 are provided on a plurality of semiconductor layers 300, 400and 500, a phosphor 1000 is provided on opposite side thereof. The metalreflective film 904 and an n-side bonding pad 800 are electricallyconnected with external electrodes 1100 and 1200. The externalelectrodes 1100 and 1200 can be lead frames for a package, or electricalpatterns provided on the COB (Chip on Board) or PCB (Printed CircuitBoard). The phosphor 1000 can be coated conformally, or can be mixedwith an epoxy resin and then used to cover the external electrodes 1100and 1200. The phosphor 1000 absorbs light that is generated in theactive layer, and converts this light to a light of longer or shorterwavelength.

SUMMARY

The problems to be solved by the present disclosure will be described inthe latter part of the best mode for carrying out the invention.

This section provides a general summary of the present disclosure and isnot a comprehensive disclosure of its full scope or all of its features.

According to one aspect of the present disclosure, there is provided asemiconductor light emitting device, comprising: a plurality ofsemiconductor layers, including a first semiconductor layer having afirst conductivity, a second semiconductor layer having a secondconductivity different from the first conductivity, and an active layerinterposed between the first semiconductor layer and the secondsemiconductor layer, generating light via electron-hole recombination; afirst electrode, supplying either electrons or holes to the plurality ofsemiconductor layers; a second electrode, supplying, to the plurality ofsemiconductor layers, electrons if the holes are supplied by the firstelectrode, or holes if the electrons are supplied by the firstelectrode; a non-conductive distributed bragg reflector coupled to theplurality of semiconductor layers, reflecting the light from the activelayer; and a first light-transmitting film coupled to the distributedbragg reflector from a side opposite to the plurality of semiconductorlayers with respect to the non-conductive distributed bragg reflector,wherein the first light-transmitting film has a refractive index lowerthan an effective refractive index of the distributed bragg reflector.

According to another aspect of the present disclosure, there is provideda semiconductor light emitting device comprising: a plurality ofsemiconductor layers that grows sequentially on a growth substrate, withthe plurality of semiconductor layers including a first semiconductorlayer having a first conductivity, a second semiconductor layer having asecond conductivity different from the first conductivity, and an activelayer interposed between the first semiconductor layer and the secondsemiconductor layer, generating light via electron-hole recombination; afirst electrode supplying either electrons or holes to the plurality ofsemiconductor layers; a second electrode supplying, to the plurality ofsemiconductor layers, electrons if the holes are supplied by the firstelectrode, or holes if the electrons are supplied by the firstelectrode; a non-conductive reflective film, which is formed on thesecond semiconductor layer, for reflecting light from the active layertowards the first semiconductor layer on the side of the growthsubstrate and includes a dielectric film and a distributed braggreflector in order mentioned from the second semiconductor layer; and alight-transmitting film formed on the distributed bragg reflector aspart of or separately from the non-conductive reflective film, whereinthe light-transmitting film has a refractive index lower than aneffective refractive index of the distributed bragg reflector.

The advantageous effects of the present disclosure will be described inthe latter part of the best mode for carrying out the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating an example of the semiconductor lightemitting device proposed in U.S. Pat. No. 7,262,436.

FIG. 2 is a view illustrating an example of the semiconductor lightemitting device proposed in JP Pub. No. 2006-120913.

FIG. 3 to FIG. 5 are views illustrating an example of the semiconductorlight emitting device according to the present disclosure.

FIG. 6 is a view illustrating another example of the semiconductor lightemitting device according to the present disclosure.

FIG. 7 is a view illustrating still another example of the semiconductorlight emitting device according to the present disclosure.

FIG. 8 is a view illustrating still another example of the semiconductorlight emitting device according to the present disclosure.

FIG. 9 and FIG. 10 are views illustrating further examples of thesemiconductor light emitting device according to the present disclosure.

FIG. 11 is a view illustrating yet another example of the semiconductorlight emitting device according to the present disclosure.

FIG. 12 is a view illustrating an example of the semiconductor lightemitting device proposed in JP Pub. No. 2009-164423.

FIG. 13 is a view illustrating yet another example of the semiconductorlight emitting device according to the present disclosure.

FIG. 14 is a cross section view taken along line A-A of FIG. 13.

FIG. 15 is a cross section view taken along line B-B of FIG. 13.

FIG. 16 is a view illustrating the semiconductor light emitting deviceof FIG. 13, without the p-side and n-side electrodes and thenon-conductive reflective film.

FIG. 17 is a view illustrating yet another example of the semiconductorlight emitting device according to the present disclosure.

FIG. 18 is a cross section view taken along line D-D of FIG. 17.

FIG. 19 is a cross section view taken along line E-E of FIG. 17.

FIG. 20 is a view illustrating a state of two semiconductor lightemitting devices before they are divided into individual semiconductorlight emitting devices, during the manufacturing process of asemiconductor light emitting device.

FIG. 21 is a view illustrating a state of two semiconductor lightemitting devices after they are divided into individual semiconductorlight emitting devices, during the manufacturing process of asemiconductor light emitting device.

FIG. 22 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 23 is a cross section view taken along line A-A′ of FIG. 22.

FIG. 24 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 25 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 26 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 27 is an enlarged view of the area where an electrical connectionis formed.

FIG. 28 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 29 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 30 graphically shows reflectivity as a function of wavelengths ofaluminum (Al), silver (Ag) and gold (Au).

FIG. 31 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 32 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 33 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 34 and FIG. 35 are views illustrating still other examples of thesemiconductor light emitting device according to the present disclosure.

FIG. 36 to FIG. 38 are views illustrating an exemplary process formanufacturing the semiconductor light emitting device shown in FIG. 34.

FIG. 39 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 40 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 41 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 42 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 43 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.

FIG. 44 is a view illustrating a relation among a dielectric film, adistributed bragg reflector and an electrode in the semiconductor lightemitting device shown in FIG. 7.

FIG. 45 is a view illustrating a relation among a dielectric film havingan optical waveguide incorporated therein, a distributed bragg reflectorand an electrode in the semiconductor light emitting device shown inFIG. 7.

FIG. 46 is a view illustrating one example of the semiconductor lightemitting device into which the optical waveguide described in FIG. 45 isincorporated.

FIG. 47 illustrates a conceptual view of the semiconductor lightemitting device to which an optical waveguide according to the presentdisclosure is applied.

FIG. 48 is a view illustrating another example of the semiconductorlight emitting device to which an optical waveguide according to thepresent disclosure is applied.

FIG. 49 is a view illustrating yet another example of the semiconductorlight emitting device to which an optical waveguide according to thepresent disclosure is applied.

FIG. 50 is a view illustrating still another example of thesemiconductor light emitting device to which an optical waveguideaccording to the present disclosure is applied.

DETAILED DESCRIPTION

The present disclosure will now be described in detail with reference tothe accompanying drawings.

FIG. 3 to FIG. 5 are views illustrating an example of the semiconductorlight emitting device according to the present disclosure, in which FIG.3 is a cross section view taken along line A-A of FIG. 4, and FIG. 5 isa cross section view taken along line B-B of FIG. 4. For the sake ofconvenient explanation, a non-conductive reflective film 91 and anelectrode 92 are not shown in FIG. 4.

The semiconductor light emitting device includes a substrate 10, abuffer layer 20 grown on the substrate 10, an n-type semiconductor layer30 grown on the buffer layer 20, an active layer grown on the n-typesemiconductor layer 30, generating light via electron-holerecombination, and a p-type semiconductor layer 50 grown on the activelayer 40. The substrate 10, which can eventually be removed, is mainlymade of sapphire, SiC, Si, GaN or the like, and the buffer layer 20 canbe omitted. When the substrate 10 is removed or has conductivity, anelectrode 80 may be formed on the n-type semiconductor layer 30 sideafter the substrate 10 is removed therefrom, or on the conductivesubstrate 10 side. The positions of the n-type semiconductor layer 30and the p-type semiconductor layer 50 can be changed with each other.For a group III nitride semiconductor light emitting device, thosesemiconductor layers are mainly made of GaN. Each of the semiconductorlayers 20, 30, 40 and 50 can be configured in a plurality of sub layers,and the semiconductor light emitting device may also have an additionalsemiconductor layer. In addition to the electrode 80 that provideselectrons to the n-type semiconductor layer 30, the semiconductor lightemitting device includes an electrode 92 that provides holes to thep-type semiconductor layer 50. A finger electrode 81 extended into then-type semiconductor layer 30 forms a part of the electrode 80. Theelectrode 80 may have an additional bump that makes the electrode 80sufficiently high enough to be coupled with a package, or the electrode80 per se may be deposited up to a height where it can be coupled with apackage as shown in FIG. 2. In order to reflect light from the activelayer 40 towards the substrate 10 used for the growth or towards then-type semiconductor layer 30 if the substrate 10 has been removed, anon-conductive reflective film 91 is provided over the p-typesemiconductor layer 50. Also, the non-conductive reflective film 91 maybe formed on the n-type semiconductor layer 30 exposed by etching, andon a portion of the electrode 80. A person skilled in the art shouldunderstand that it is not absolutely necessary for the non-conductivereflective film 91 to cover the entire area over the semiconductorlayers 30 and 50 on the opposite side of the substrate 10. Thenon-conductive reflective film 91 serves as a reflective film, yet itcan preferably be composed of a light-transmitting material, forexample, a light-transmitting dielectric material such as SiO_(x),TiO_(x), Ta₂O₅ or MgF₂, in order to avoid the light absorption. When thenon-conductive reflective film 91 is composed of SiO_(x), its refractiveindex is lower than that of the p-type semiconductor layer 50 (e.g.,GaN) such that it can reflect part of the light having an incidenceangle greater than a critical angle towards the semiconductor layers 30,40 and 50. When the non-conductive reflective film 91 is composed of aDBR (e.g., DBR composed of the combination of SiO₂ and TiO₂), it canreflect a greater amount of light towards the semiconductor layers 30,40 and 50. In FIG. 7, the non-conductive reflective film 91 has a doublelayer structure having a DBR 91 a and a dielectric film 91 b with arefractive index lower than that of the p-type semiconductor layer 50.As the deposition of the DBR 91 a needs to be done with high precision,the dielectric film 91 b having a uniform thickness is first formedbefore the deposition. As such, despite heterogeneous deposits 50, 60,80, 81 and 93 of different forms which are present on the semiconductorlayers 30, 40 and 50, the DBR 91 b can be prepared in a stable manner,and light reflection can also benefit therefrom. The dielectric film 91b is suitably made of SiO₂ and it has a thickness suitably ranging from0.2 μm to 1.0 μm. When the DBR 91 a is composed of TiO₂/SiO₂, each layeris designed to have an optical thickness of one-fourth of a givenwavelength, and the number of its combinations is suitably between 4 and20 pairs. Further, the finger electrode 93 has a height suitably rangingfrom 0.5 μm to 4.0 μm. If the finger electrode is thinner than therange, it can lead to an increased operating voltage; and if the fingerelectrode is thicker than the range, it can affect the stability of theprocess and increase the material cost. Considering that the electrode92 contributes to reflecting light from the active layer 30 towards thesubstrate 10 or towards the n-type semiconductor layer 30, it ispreferably a conductive reflective film that covers all or almost all ofthe non-conductive reflective film 91 over the p-type semiconductorlayer 50. To this end, metals having a high reflectance, such as Al orAg, may be utilized. A finger electrode 93 is extended between thenon-conductive reflective film 91 and the p-type semiconductor layer 50,for supplying current (holes, to be precise) from the electrode 92 tothe p-type semiconductor layer 50. The introduction of the fingerelectrode 93 provides a foundation for realizing a flip-chip that hasovercome all the problems imposed by the flip-chips in FIG. 1 and FIG.2. For electrical communication between the electrode 92 and the fingerelectrode 93 which are separated by the non-conductive reflective film91 interposed between them, an electrical connection 94 is prepared inthe vertical direction, passing through the non-conductive reflectivefilm 91. Without the finger electrode 93, a number of electricalconnections 94 will have to be connected directly to alight-transmitting conductive film 60 that is prepared on almost theentire face of the p-type semiconductor layer 50. In this case, however,it is not easy to form an acceptable electrical contact between theelectrode 92 and the light-transmitting conductive film 60, and manyproblems might be created during the manufacturing process. In thisregard, the present disclosure forms the finger electrode 93, prior tothe formation of the non-conductive reflective film 91 and the electrode92, on the p-type semiconductor layer 50 or preferably on thelight-transmitting conductive film 60 and then performs thermaltreatment on the finger electrode 93, such that a stable electricalcontact can be created between both. While Al or Ag having a highreflectance is a suitable material for the electrode 92, materials suchas Cr, Ti, Ni or alloys thereof also may be suitable for the stableelectrical contact. Accordingly, by introducing the finger electrode 93,it makes it easy to meet the required design specifications. A personskilled in the art should understand that Al or Ag having a highreflectance can also be used for the finger electrode 93. As describedabove, the light-transmitting conductive film 60 is preferably provided.Especially, a p-type GaN has a poor current spreading capability, andwhen the p-type semiconductor layer 50 is composed of GaN, thelight-transmitting conductive film 60 needs to be incorporated in mostcases. For instance, materials such as ITO, Ni/Au or the like can beused for the light-transmitting conductive film 60. When the height ofthe finger electrode 93 reaches the electrode 92, the finger electrode93 per se forms the electrical connection 94. Although it is possible toenvisage configuring the electrode 92 with the same manner as a p-sidebonding pad 700 as shown in FIG. 2, it would not be desirable as thep-side bonding pad 700 absorbs light, and the area of the non-conductivereflective film 91 is reduced. A person skilled in the art shouldunderstand that the electrode 92 can also be formed by a mounting faceat the package level, following the manufacturing of a chip. It shouldbe noted that all of the components mentioned hitherto will suffice toform the semiconductor light emitting device according to the presentdisclosure. However, since part of the light generated in the activelayer 40 can be absorbed by the finger electrode 93, to avoid this, itis preferable to provide an optical absorption barrier 95 below thefinger electrode 93. The optical absorption barrier 95 may only serve toreflect part or all of the light generated in the active layer 40, ormay only serve to prevent the current from the finger electrode 93 fromflowing to immediately below zone of the finger electrode 93, or mayserve both functions. To perform these functions, the optical absorptionbarrier 95 can have a single layer (e.g., SiO₂) or a multilayer (e.g.,SiO₂/TiO₂/SiO₂) that is made of a light-transmitting material(s) havinga refractive index lower than that of the p-type semiconductor layer 50,or a DBR or any combination of the single layer and the DBR. Inaddition, the optical absorption barrier 95 can be composed of anon-conductive material (e.g., a dielectric film such as SiO_(x),TiO_(x) or the like). Therefore, although it is not always required toform the optical absorption barrier 95 with a light-transmittingmaterial or with a non-conductive material, the effects thereof can beincreased by incorporating a light-transmitting dielectric film.

FIG. 6 is a view illustrating another example of the semiconductor lightemitting device according to the present disclosure, in which alight-transmitting conductive film 60 has openings 96 to enable anon-conductive reflective film 91 to contact with a p-type semiconductorlayer 50. The openings 96 can have any shape, including a plurality ofislands, bands and the like. Even if the light-transmitting conductivefilm 60 is composed of most common ITO, it absorbs part of the lightgenerated in the active layer 40. However, the formation of the openings96 makes it possible to reduce the light absorption by thelight-transmitting conductive film 60. While current spreading into theentire p-type semiconductor layer 50 might not be sufficient, it can becomplemented by the finger electrode 93. No description will be providedfor like reference numerals that have been explained above.

FIG. 8 is a view illustrating still another example of the semiconductorlight emitting device according to the present disclosure, whichincludes an electrical connection 82 passing through the substrate 10,the buffer layer 20 and the n-type semiconductor layer 30, and anelectrode 83 on the substrate 10 or the n-type semiconductor layer 30after the substrate 10 is removed therefrom, i.e. on the n-typesemiconductor layer 30 side. This configuration enables to form anon-conductive reflective film 91 and an electrode 92 over the whole ofplural semiconductor layers 30 and 50 on the opposite side of thesubstrate 10.

FIG. 9 and FIG. 10 are views illustrating further examples of thesemiconductor light emitting device according to the present disclosure.In these examples, as the light-transmitting conductive film 60 iseliminated, the finger electrode 93 comes in direct contact with theoptical absorption barrier 95.

FIG. 11 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure.Unlike the example of FIG. 5, the semiconductor light emitting devicedoes not include the optical absorption barrier 95.

FIG. 13 is a view illustrating yet another example of the semiconductorlight emitting device according to the present disclosure, FIG. 14 is across section view taken along line A-A of FIG. 13, and FIG. 15 is across section view taken along line B-B of FIG. 13. FIG. 16 is a viewillustrating the semiconductor light emitting device of FIG. 13, withoutthe p-side and n-side electrodes and the non-conductive reflective film.

The semiconductor light emitting device 1 includes a substrate 10, abuffer layer 20 grown on the substrate 10, an n-type semiconductor layer30 grown on the buffer layer 20, an active layer 40 grown on the n-typesemiconductor layer 30, generating light via electron-holerecombination, and a p-type semiconductor layer 50 grown on the activelayer 40.

The substrate 10, which can eventually be removed, is mainly made ofsapphire, SiC, Si, GaN or the like, and the buffer layer 20 can beomitted. When the substrate 10 is removed or has conductivity, an n-sideelectrode 80 may be formed on the n-type semiconductor layer 30 sideafter the substrate 10 is removed therefrom, or on the conductivesubstrate 10 side. The positions of the n-type semiconductor layer 30and the p-type semiconductor layer 50 can be changed with each other.For a group III nitride semiconductor light emitting device, thosesemiconductor layers are mainly made of GaN. Each of the semiconductorlayers 20, 30, 40 and 50 can be configured in a plurality of sub layers.The semiconductor light emitting device may also have an additionalsemiconductor layer.

Portions of the p-type semiconductor layer 50 and the active layer 40are removed by a mesa etching process to form two n-side contact areas31 where the n-type semiconductor layer 30 is exposed. An n-side fingerelectrode 81 is then formed on the n-type semiconductor layer 30 withineach n-side contact area 31. The n-side contact areas 31 are extended inparallel with one side C of the semiconductor light emitting device.While the n-side contact areas 31 may be open to one of the lateraldirections of the semiconductor light emitting device, they arepreferably enclosed and blocked by the active layer 40 and the p-typesemiconductor layer 50 without being open to any one of the lateraldirections. The number of the n-side contact areas 31 may be increasedor decreased, and the array configuration thereof can be varied. Then-side finger electrode 81 preferably includes a branch portion 88extended lengthily, and a connecting portion 89 formed at one end of thebranch portion 88 and having a greater width. As such, the n-sidecontact area 31 has a smaller width at the part where the branch portion88 of the n-side finger electrode 81 is disposed and a greater width atthe part where the connecting portion 89 of the n-side finger electrode81 is disposed.

Three p-side finger electrodes 93 are formed on the p-type semiconductorlayer 50. The p-side finger electrodes 93 are formed in parallel withthe n-side finger electrodes 81, in which one of the p-side fingerelectrodes is arranged between two n-side finger electrodes 81 and theother two p-side finger electrodes are arranged on both sides of then-side finger electrodes, respectively. Thus, the n-side fingerelectrodes 81 are placed among the p-side finger electrodes 93,respectively, in an alternate manner. Also, the p-side finger electrode93 preferably includes a branch portion 98 extended lengthily, and aconnecting portion 99 formed at one end of the branch portion 98 andhaving a greater width. Meanwhile, as shown in FIG. 13, the connectingportion 99 of the p-side finger electrode 93 is placed on the oppositeside of the connecting portion 89 of the n-side finger electrode 81,when the semiconductor light emitting device is seen from the top. Thatis to say, the connecting portion 99 of the p-side finger electrode 93is placed on the left side, while the connecting portion 89 of then-side finger electrode 81 is placed on the right side. The p-sidefinger electrode 93 extends along the direction of one side C of thesemiconductor light emitting device. For instance, in FIG. 13 and FIG.16, it is extended from the left side to the right side. With theseplural p-side finger electrodes 93 extended lengthily, the device can beplaced on a mount part (e.g., a sub-mount, a package, or a COB (Chip onBoard)) in an upside-down position without inclination. In this regard,it is preferable to form the p-side finger electrode 93 as long aspossible.

A suitable height for the p-side finger electrodes 93 and the n-sidefinger electrodes 81 ranges from 2 μm to 3 μm. If the finger electrodesare thinner than the range, it can lead to an increased operatingvoltage; and if the finger electrodes are thicker than the range, it canaffect the stability of the process and increase the material cost.

Preferably, prior to the formation of the p-side finger electrode 93, anoptical absorption barrier 95 is formed on the p-type semiconductorlayer 50 on which the p-side finger electrode 93 is supposed to beformed. The optical absorption barrier 95 is formed in such a way thatit is slightly wider than the p-side finger electrode 93. Thelight-absorption preventing layer 95 serves to prevent the p-side fingerelectrode 93 from absorbing light that is generated in the active layer40. The optical absorption barrier 95 may only serve to reflect part orall of the light generated in the active layer 40, or may only serve toprevent the current from the finger electrode 93 from flowing toimmediately below zone of the finger electrode 93, or may serve bothfunctions. To perform these functions, the optical absorption barrier 95can be composed of a single layer (e.g., SiO₂) or a multilayer (e.g.,SiO₂/TiO₂/SiO₂) that is made of a light-transmitting material having arefractive index lower than that of the p-type semiconductor layer 50,or a DBR or a combination of the single layer and the DBR. In addition,the optical absorption barrier 95 can be composed of a non-conductivematerial (e.g., a dielectric film such as SiO_(x), TiO_(x) or the like).Depending on the structure, a suitable thickness for the opticalabsorption barrier 95 is between 0.2 μm and 3.0 μm. If the opticalabsorption barrier 95 is thinner than the range, it cannot functionproperly; and if the optical absorption barrier 95 is thicker than therange, it can be difficult to deposit the light-transmitting conductivefilm 60 on the optical absorption barrier 95. Although the opticalabsorption barrier 95 does not always have to be composed of alight-transmitting material or of a non-conductive material, the effectsthereof can be increased by incorporating a light-transmittingdielectric material.

Preferably, following the formation of the optical absorption barrier 95and prior to the formation of the p-side finger electrode 93, thelight-transmitting conductive film 60 is formed on the p-typesemiconductor layer 50. The light-transmitting conductive film 60 isformed on the p-type semiconductor layer 50 in such a way that it coversalmost the entire p-type semiconductor layer, except for the n-sidecontact area 31 that is formed by a mesa etching process. As such, theoptical absorption barrier 95 is interposed between thelight-transmitting conductive film 60 and the p-type semiconductor layer50, especially in case of a p-type GaN, where it has a poor currentspreading capability. Also, when the p-type semiconductor layer 50 iscomposed of GaN, the light-transmitting conductive film 60 should beincorporated in most cases. For instance, materials such as ITO, Ni/Auor the like can be used for the light-transmitting conductive film 60.After the light-transmitting conductive film 60 is formed, the p-sidefinger electrode 93 can be formed on the light-transmitting conductivefilm 60 where the optical absorption barrier 95 is placed.

Following the formation of the n-side finger electrode 81 and the p-sidefinger electrode 93, a non-conductive reflective film 91 is formed insuch a way that the n-side contact area 31 including the n-side fingerelectrode 81 and the p-type semiconductor layer 50 including the p-sidefinger electrode 93 are covered overall. The non-conductive reflectivefilm 91 serves to reflect light from the active layer 40 towards thesubstrate 10 used for the growth or towards the n-type semiconductorlayer 30 if the substrate 10 has been removed. Preferably, thenon-conductive reflective film 91 also covers the exposed side faces ofthe p-type semiconductor layer 50 and the active layer 40 that connectthe upper face of the p-type semiconductor layer 50 and the upper faceof the n-side contact area 31. A person skilled in the art shouldunderstand that it is not absolutely necessary for the non-conductivereflective film 91 to cover the entire area over the exposed n-typesemiconductor layer 30 as a result of etching and the p-typesemiconductor layer 50 on the opposite side of the substrate 10.

The non-conductive reflective film 91 serves as a reflective film, yetit can preferably be composed of a light-transmitting material, forexample, a light-transmitting dielectric material such as SiO_(x),TiO_(x), Ta₂O₅ or MgF₂, in order to avoid the light absorption. Thenon-conductive reflective film 91 can have a variety of structures,including a single dielectric film, for example, made of alight-transmitting dielectric material such as SiO_(x), a single DBR,for example, including the combination of SiO₂ and TiO₂, heterogeneousplural dielectric films and any combination of a dielectric film and aDBR, and can have a thickness ranging from 3 to 8 μm, for example. Thedielectric film having a refractive index lower than that of the p-typesemiconductor layer 50 (e.g., GaN) can reflect part of the light havingan incidence angle greater than a critical angle towards the substrate10, the DBR can reflect a greater amount of light towards the substrate10, and the DBR can also be designed for a specific wavelength such thatit can effectively reflect light in response to the wavelength of thelight generated.

Preferably, as shown in FIG. 14 and FIG. 15, the non-conductivereflective film 91 has a double layer structure including a DBR 91 a anda dielectric film 91 b. As the deposition of the DBR 91 a needs to bedone with high precision, the dielectric film 91 b having a uniformthickness is first formed before the deposition such that the DBR 91 bcan be prepared in a stable manner, and light reflection can alsobenefit therefrom.

During the formation of a semiconductor light emitting device accordingto the present disclosure, a step (step-shape portion) having heightdifference can be created by a mesa etching process for forming then-side contact area 31, a component such as the p-side finger electrode93 or the n-side finger electrode 81 with a step is required, and evenafter the non-conductive reflective film 91 is formed, it should besubjected to a boring process to make an opening in it as described indetail below. Thus, special attention should be paid during theformation of the dielectric film 91 b.

The dielectric film 91 b is suitably made of SiO₂, and it preferably hasa thickness between 0.2 μm and 1.0 μm. If the dielectric film 91 b isthinner than the range, it is not enough to fully cover the n-sidefinger electrode 81 and p-side finger electrode 93 having a heightranging from 2 μm to 3 μm; and if the dielectric film 91 b is thickerthan the range, the subsequent boring process can be difficult toperform. The dielectric film 91 b may be thicker than the following DBR91 a. Moreover, it is necessary to form the dielectric film 91 b by amore suitable method for ensuring the reliability of the device. Forinstance, the dielectric film 91 b made of SiO₂ is preferably formed byCVD (Chemical Vapor Deposition) and in particular by PECVD (PlasmaEnhanced CVD). This is because the steps are created during theformation of the n-side contact area 31 by mesa etching, the p-sidefinger electrode 93 and the n-side finger electrode 81, and because theCVD is more advantageous than PVD (Physical Vapor Deposition) such asE-beam evaporation to cover the steps. More specifically, when thedielectric film 91 b is formed by E-beam evaporation, the dielectricfilm 91 b can be formed more thinly on the lateral faces of the p-sidefinger electrode 93 and n-side finger electrode 81 having the step, oron the tilted step face generated by mesa etching. Meanwhile, if athinner dielectric film 91 b is formed on the step faces, and especiallyif the p-side finger electrode 93 and the n-side finger electrode 81 aredisposed below the p-side electrode 92 and the n-side electrode 80respectively as described below, a short might occur between theelectrodes. Therefore, in order to ensure insulation, the dielectricfilm 91 b is preferably formed by CVD. In this way, it is possible tosecure the reliability of the semiconductor light emitting device, whileensuring those functions as the non-conductive reflective film 91.

The DBR 91 a is formed on the dielectric film 91 b and composes thenon-conductive reflective film 91, together with the dielectric film 91b. For example, the DBR 91 a having a repeatedly laminated structurecomposed of the combination of TiO₂/SiO₂ is preferably formed by PVD,and in particular by E-beam evaporation, sputtering or thermalevaporation. When the DBR 91 a is composed of the combination ofTiO₂/SiO₂, each layer is designed to have an optical thickness of onefourth of a given wavelength, and the number of its combinations issuitably between 4 and 20 pairs. If the number of pairs is smaller thanthe range, the reflectivity of the DBR 91 a may be degraded; and if thenumber of pairs is larger than the range, the DBR 91 a may becomeexcessively thick.

With the non-conductive reflective film 91 thus formed, the p-sidefinger electrode 93 and the n-side finger electrode 81 are fully coveredby the non-conductive reflective film 91. To enable the p-side fingerelectrode 93 and the n-side finger electrode 81 to electricallycommunicate with the p-side electrode 92 and the n-side electrode 80described below, openings passing through the non-conductive reflectivefilm 91 are formed, and the openings are then filled with an electrodematerial to form electrical connections 94 and 82. These openings arepreferably formed by dry etching or wet etching or both. As the p-sidefinger electrode 93 and the n-side finger electrode 81 have narrow-widthbranch portions 98 and 88 respectively, the electrical connections 94and 82 are preferably formed on the connecting parts 99 and 89 of thep-side finger electrode 93 and the n-side finger electrode 81,respectively. In absence of the p-side finger electrode 93, a number ofelectrical connections 94 should be formed and connected directly to thelight-transmitting conductive film 60 that is prepared on almost theentire face of the p-type semiconductor layer 50. Likewise, in absenceof the n-side finger electrode 81, a number of electrical connections 82should be formed and connected directly to the n-side contact area 31.However, it is difficult to form a satisfactory electrical contactbetween the p-side electrode 92 and the light-transmitting conductivefilm 60 and between the n-side electrode 80 and the n-type semiconductorlayer 30, and many problems also occur during the manufacturing process.Meanwhile, according to the present disclosure, prior to the formationof the non-conductive reflective film 91, the n-side finger electrode 81is formed on the n-side contact area 31, and the p-side finger electrode93 is formed either on the p-type semiconductor layer 50 or preferablyon the light-transmitting conductive film 60, and these electrodes arethen subjected to heat treatment, thereby making a stable electricalcontact between both sides.

Once the electrical connections 94 and 82 are formed, it is desirable toform the p-side electrode 92 and the n-side electrode 80 on thenon-conductive reflective film 91. Considering that the p-side electrode92 and the n-side electrode 80 contribute to reflecting light from theactive layer 40 towards the substrate 10, those electrodes are formedover a broad area to be able to cover the entire or almost the entireupper face of the non-conductive reflective film 91, thereby serving asa conductive reflective film. However, the p-side electrode 92 and then-side electrode 80 are preferably formed at a distance from each otheron the non-conductive reflective film 91. As such, there exists aportion on the non-conductive reflective film 91, which is coveredneither by the p-side electrode 92 nor by the n-side electrode 80. Whilethe p-side electrode 92 or the n-side electrode 80 may suitably be madeof a material having an acceptable reflectance (e.g., Al, Ag or thelike), it is preferably made of the combination of the high-reflectancematerial (e.g., Al, Ag or the like) and Cr, Ti, Ni, Au or any alloythereof for obtaining a stable electrical contact. The p-side electrode92 and the n-side electrode 80 serve to supply current to the p-sidefinger electrode 93 and the n-side finger electrode 81 to connect thesemiconductor light emitting device with external equipment; and, byoccupying a broad area, to reflect the light from the active layer 40and/or emit the heat. Therefore, forming both the p-side electrode 92and the n-side electrode 81 on the non-conductive reflective film 91makes it possible to minimize the height difference between the p-sideelectrode 92 and the n-side electrode 80, and is advantageous when thesemiconductor light emitting device according to the present disclosureis bonded to a mount part (e.g., a sub-mount, a package or a COB). Thisadvantage becomes more apparent especially when the eutectic bondingmethod is applied.

As the p-side electrode 92 and the n-side electrode 80 are formed over abroad area on the non-conductive reflective film 91, both the p-sidefinger electrode 93 and the n-side finger electrode 81 are placedbeneath the non-conductive reflective film 91. Here, the p-side fingerelectrode 93 extends lengthily passing below the n-side electrode 80placed directly on the non-conductive reflective film 91, and the n-sidefinger electrode 81 extends lengthily passing below the p-side electrode92 placed directly on the non-conductive reflective film 91. As thenon-conductive reflective film 91 exists between the p-side electrode 92and the p-side finger electrode 93, and between the n-side electrode 80and the n-side finger electrode 81, a short between the electrodes 92and 80 and the finger electrodes 93 and 81 can be prevented. Further, byintroducing the p-side finger electrode 93 and the n-side fingerelectrode 81 as described above into the formation of a flip-chip, itbecomes possible to supply current to the semiconductor layer areas ofinterest, without restriction.

In general, the p-side electrode 92, the n-side electrode 80, the p-sidefinger electrode 93 and the n-side finger electrode 81 are composed of aplurality of metal layers, respectively. In case of the p-side fingerelectrode 93, the bottom layer thereof should have a high bondingstrength with the light-transmitting conductive film 60. To this end,materials such as Cr or Ti are mainly used, but other materials such asNi, Ti or TiW can also be used as there are no particular limitationsregarding this matter. A person skilled in the art should understandthat Al or Ag having a high reflectance can also be employed for thep-side finger electrode 93 and the n-side finger electrode 81. In caseof the p-side electrode 92 and the n-side electrode 80, Au is used fortheir top layers for wire bonding or for the connection with an externalelectrode. Meanwhile, in order to reduce the amount of Au used and tocomplement a relatively low hardness of Au, other material such as Ni,Ti, TiW or W, depending on the specifications required, or Al or Ag,when a high reflectance is required, can be employed between the bottomlayer and the top layer. In the present disclosure, since the p-sidefinger electrode 93 and the n-side finger electrode 81 need to beelectrically connected to the electrical connections 94 and 82, Au couldbe considered for use as the top layers for finger electrodes 93 and 81.However, the inventors found out that it is not appropriate to use Au asthe top layers for the p-side finger electrode 93 and the n-side fingerelectrode 81, because the Au gets easily peeled off due to a weakbonding strength between the Au and the non-conductive reflective film91 at the time of deposition of the non-conductive reflective film 91onto the Au top layer. To resolve this problem, other material such asNi, Ti, W, TiW, Cr, Pd or Mo can be employed in place of Au to form thetop layers of the finger electrodes. In this way, the bonding strengthbetween the top layers and the non-conductive reflective film 91 to bedeposited on the top layers is retained and the reliability can thus beimproved. Further, those metals mentioned above are fully capable offunctioning as a diffusion barrier during the formation of an opening inthe non-conductive reflective film 91 to create the electricalconnection 94, which can be helpful for ensuring the stability of thesubsequent processes and the electrical connections 94 and 82.

FIG. 17 is a view illustrating yet another example of the semiconductorlight emitting device according to the present disclosure, FIG. 18 is across section view taken along line D-D of FIG. 17, and FIG. 19 is across section view taken along line E-E of FIG. 17.

In a semiconductor light emitting device 2 according to the presentdisclosure, as shown in FIG. 18 and FIG. 19, a non-conductive reflectivefilm 91 further includes, in addition to a dielectric film 91 b and aDBR 91 a, a clad film 91 f to be formed on the DBR 91 a. Although alarge portion of light generated in the active layer 40 is reflected bythe dielectric film 91 b and the DBR 91 a towards an n-sidesemiconductor layer 30, part of the light is trapped inside thedielectric film 91 b and the DBR 91 a as they also have a certainthickness, or emitted through the lateral faces of the dielectric film91 b and the DBR 91 b. The inventors tried to analyze the relation amongthe dielectric film 91 b, the DBR 91 a and the clad film 91 f, from theperspective of an optical waveguide. The optical waveguide is astructure that encloses a propagation part of light by a material havinga refractive index lower than that of the propagation part of light andguides the light utilizing total reflection. In this regard, if the DBR91 a is considered as the propagation part, the dielectric film 91 b andthe clad film 91 f can be regarded as part of the structure thatencloses the propagation part. When the DBR 91 a is composed ofSiO₂/TiO₂, with SiO₂ having a refractive index of 1.46 and TiO₂ having arefractive index of 2.4, an effective refractive index (which denotes anequivalent refractive index of light that can travel in a waveguide thatis made of materials having different refractive indices, and has avalue between 1.46 and 2.4) of the DBR 91 a is higher than that of thedielectric film 91 b composed of SiO₂. The clad film 91 f is alsocomposed of a material having an effective refractive index lower thanthat of the DBR 91 a. Preferably, the clad film 91 f has a thicknesswhich desirably ranges from λ/4n to 3.0 μm, in which A denotes awavelength of the light generated in the active layer 40, and n denotesa refractive index of a material composing the clad film 91 f. By way ofexample, the clad film 91 f can be composed of a dielectric such as SiO₂having a refractive index of 1.46. When A is 450 nm (4500 Å), the cladfilm 91 f can be formed in a thickness of 771 Å (4500/4×1.46=771 Å) ormore. Considering that the top layer of the DBR 91 a made of multiplepairs of SiO₂/TiO₂ can be composed of a SiO₂ layer having a thickness ofλ/4n, it is desirable that the clad film 91 f is thicker than λ/4n to bedistinguished from the top layer of the DBR 91 a that is placed beneaththe clad film 91 f. Although it is not desirable for the top layer ofthe DBR 91 a to be too thick (e.g., 3 μm or more), imposing a burden onthe subsequent boring process and only increasing the material costwithout contributing to the improvement of the efficiency, it is notimpossible, depending on the case, to make the top layer as thick as 3.0μm or more. When the DBR 91 a comes in direct contact with the p-sideelectrode 92 and the n-side electrode 80, part of the light travellingthrough the DBR 91 a may be affected by the p-side electrode 92 and then-side electrode 80 and then absorbed. However, interposing the cladfilm 91 f having a refractive index lower than that of the DBR 91 abetween the p- and n-side electrodes (92, 80) and the DBR 91 a canminimize the partial absorption of the light traveling through the DBR91 a by the p-side electrode 92 and the n-side electrode 80, therebyincreasing the efficiency of light extraction. Accordingly, the cladfilm 91 f should generally have at least a thickness corresponding tothe wavelength of light to achieve the effect described above, andtherefore it preferably has a thickness of at least λ/4n. Meanwhile, ifthere is a big difference between the refractive index of the DBR 91 aand the refractive index of the clad film 91 f, the DBR 91 a mayrestrict light more strongly such that a thinner clad film 91 f could beused. However, if the difference between the refractive indices issmall, the clad film 91 f needs to be sufficiently thick to obtain theeffect described above. Thus, the thickness of the clad film 91 f isdetermined with full consideration of a difference between therefractive index of a material constituting the clad film 91 f and theeffective refractive index of the DBR 91 a. For instance, if the cladfilm 91 f is composed of SiO₂ and the DBR 91 a is composed of SiO₂/TiO₂,a suitable thickness for the clad film 91 f will be at least 0.3 μm tobe distinguished from the top layer of the DBR 91 a composed of SiO₂. Onthe other hand, the upper limit of the thickness of the clad film 91 fis preferably between 1 μm and 3 μm, not to impose any burden on thesubsequent boring process.

The clad film 91 f is not particularly limited as long as its refractiveindex is lower than the effective refractive index of the DBR 91 a, andcan be composed of a metal oxide such as Al₂O₃, a dielectric film suchas SiO₂ or SiON, or other material such as MaF or CaF. If a differencein the refractive indices is small, the clad film should be made thickerto obtain the desired effect. Also, in case of using SiO₂ for the cladfilm, it is possible to use SiO₂ having a refractive index lower than1.46 to increase the efficiency.

One can envisage that the dielectric film 91 b can be omitted from thenon-conductive reflective film. Although not desirable in terms of anoptical waveguide, there is no reason to exclude the configuration ofthe non-conductive reflective film 91 composed of the DBR 91 a and theclad film 91 f, when the overall technical spirit of the presentdisclosure is taken into consideration. Also one can envisage that thenon-conductive reflective film 91 may have a TiO₂ dielectric film inplace of the DBR 91 a. Further, one can envisage that the clad film 91 fcan be omitted from the non-conductive reflective film, if the DBR 91 aincludes a SiO₂ layer on the top thereof.

The non-conductive reflective film 91, which is composed of the DBR 91 ahaving a high effective reflectance, and the dielectric film 91 b andthe clad film 91 f, each having a low reflectance, disposed on the topand bottom of the DBR 91 a, respectively, serves as an opticalwaveguide, and preferably has an overall thickness ranging from of 3 μmto 8 μm. Also, the non-conductive reflective film 91 preferably has aninclined face 91 m at the edge. This inclined face 91 m can be formed,for example, by a dry etching process. Among light rays that areincident on the non-conductive reflective film 91 that serves as anoptical waveguide, the light rays that are incident on thenon-conductive reflective film 91 at right angles or almost at rightangles are well reflected towards the substrate 10, but some light raysincluding those that are incident on the non-conductive reflective film91 at an oblique angle are not reflected towards the substrate 10 andinstead can be trapped inside the DBR 91 a that serves as a propagationpart, and then can be propagated towards the lateral face. As such, thelight rays propagated towards the lateral surface of the DBR 91 a areeither emitted to the outside or reflected towards the substrate 10, atthe inclined face 91 m of the edge of the non-conductive reflective film91. That is to say, the inclined face 91 m at the edge of thenon-conductive reflective film 91 serves as a corner reflector andcontributes to the improved luminance of the semiconductor lightemitting device. The inclined face 91 m is suitably at an angle rangingfrom 50 to 70 degrees, to facilitate the light reflection towards thesubstrate 10. The inclined face 91 m can easily be formed by wet etchingor dry etching, or both.

FIG. 20 is a view illustrating a state of two semiconductor lightemitting devices before they are divided into individual semiconductorlight emitting devices, during the manufacturing process of asemiconductor light emitting device; and FIG. 21 is a view illustratinga state of two semiconductor light emitting devices after they aredivided into individual semiconductor light emitting devices, during themanufacturing process of a semiconductor light emitting device. Forreference, those semiconductor light emitting devices 3, shown in FIG.20 and FIG. 21 for explaining the manufacturing process, are in a statewhere none of the p-side electrode 92, n-side electrode 80 and bondingpad 97 is formed.

Usually a semiconductor light emitting device is first prepared in awafer form including a plurality of semiconductor light emittingdevices, and then divided into individual semiconductor light emittingdevices by cutting, such as breaking, sawing, or scribing-and-breaking.In the scribing-and-breaking operation, the scribing process employs alaser and can be performed by focusing the laser onto the substrate sideincluding the surface and the interior of the substrate of thesemiconductor light emitting device. In this scribing process employingthe laser, the semiconductor light emitting device 3 is preliminarilycut along the boundary G of the edge of the semiconductor light device3, i.e., along the boundary G between the semiconductor light emittingdevice 3 and another neighboring semiconductor light emitting device 3.The preliminarily cut semiconductor light emitting devices arecompletely divided into individual semiconductor light emitting devicesthrough the breaking process that is performed following the scribingprocess. The breaking process is performed by applying an external forcealong the boundary G between the semiconductor light emitting device 3and another neighboring semiconductor light emitting device 3, forexample, in the direction of the substrate 10 indicated by an arrow F inFIG. 20, or in the opposite direction thereof. In this breaking process,the substrate 10 and the semiconductor layers 20, 30 40 and 50, whichare crystalline, can be cut precisely along the boundary G; while thenon-conductive reflective film 91 over the p-type semiconductor layer50, which is non-crystalline, cannot be cut precisely along the boundaryG and, in the areas around the edge of the non-conductive reflectivefilm 91, it is likely to sustain damage such as crack generationthereto. The damage of the areas around the edge of the non-conductivereflective film 91 may lead to poor yields due to those appearancedefects. Preferably, during the manufacturing of a semiconductor lightemitting device, a plurality of semiconductor light emitting devices isprepared in a wafer form, and then, prior to the scribing and brakingprocesses using a laser for dividing the semiconductor light emittingdevices into individual ones, a certain area H of the non-conductivereflective film 91 around the boundary G between a semiconductor lightemitting device and another neighboring semiconductor light emittingdevice is eliminated. In terms of the individual semiconductor lightemitting device, the certain area H of the non-conductive reflectivefilm 91 to be eliminated along the boundary G of the semiconductor lightemitting device 3 corresponds to an edge area of the non-conductivereflective film 91. The elimination of a certain area H of thenon-conductive reflective film 91 around the boundary G can alsoindicate that, before the semiconductor light emitting devices aredivided into individual ones, the non-conductive reflective film 91 ofone semiconductor light emitting device and the non-conductivereflective film 91 of another neighboring semiconductor light emittingdevice are spaced apart from each other. With a part of the areas of theedge of the non-conductive reflective film 91 being eliminated, even ifthe subsequent scribing and breaking processes may be performed using alaser, the appearance defect caused by the damaged edge of thenon-conductive reflective film 91 of each semiconductor light emittingdevice can be avoided, thereby increasing yields. For example, theelimination of a certain area H of the non-conductive reflective film 91can be carried out by dry etching, and it should be performed prior tothe breaking process in the overall semiconductor manufacturing process.However, when the openings passing through the non-conductive reflectivefilm 91 to form electrical connections 94 and 82 are formed by dryetching, it is preferable to perform the elimination at the same time.Although the inclined face 91 m serving as a corner reflector can beobtained by a separate etching process, the inclined face 91 m can beformed simultaneously in a process of eliminating the edge area of thenon-conductive reflective film 91 to avoid damage, by etching the edgeportion of the non-conductive reflective film 91 of an individualsemiconductor light emitting device.

As shown in FIG. 17 and FIG. 19, a bonding pad 97 can be present on thep-side electrode 92 and on the n-side electrode 80 respectively, as apart of each of the p-side electrode 92 and the n-side electrode 80. Thetop face of the bonding pad 97 on the p-side electrode 92 has the sameheight as the top face of the bonding pad 97 on the n-side electrode 80.That is to say, the top face of the bonding pad 97 on the p-sideelectrode 92 and the top face of the bonding pad 97 on the n-sideelectrode 80 are on the same plane. When a semiconductor light emittingdevice is coupled with external equipment by, for example, the eutecticbonding method, those bonding pads 97 allow the p-side electrode 92 andthe n-side electrode 80 to have an equal final height to thus avoid anytilting on the mount part, provide a broad and planar coupling face tothus obtain an excellent bonding strength, and dissipates the heat fromthe inside of the semiconductor light emitting device to the outside. Aplurality of bonding pads 97 can be present on the p-side electrode 92and on the n-side electrode 80, respectively, and the plurality ofbonding pads 97 are preferably formed on the portions where the n-sidefinger electrodes 81 and the p-side finger electrodes 93 are notoverlapped, i.e., between each of the n-side finger electrodes 81 andthe p-side finger electrodes 93. In other words, the bonding pads 97 areformed on the areas of the p-side electrode 92 and on the n-sideelectrode 80, except on the p-side finger electrodes 93 corresponding tothe upper most protruded portion and on the n-side finger electrodes 81corresponding to the lower most recessed portion. In addition, thebonding pad 97 can have a double layer structure including an underlyingspacer layer 97 a and a bonding layer 97 b overlying the spacer layer 97a, and have a total thickness ranging from 5 μm to 6 μm, for example. Inone example, the spacer layer 97 a may be composed of a metal layerincluding Ni, Cu or a combination thereof, and the bonding layer 97 bmay be composed of a eutectic bonding layer including a Ni/Sn, Ag/Sn/Cu,Ag/Sn, Cu/Sn or Au/Sn combination and having a thickness of aboutseveral μm. The spacer layer 97 a can serve as a wetting layer and as adiffusion barrier for a solder used in the eutectic bonding, and canalso reduce the cost burden as compared with a case where the bondingpad 97 is entirely formed of a eutectic bonding layer 97 b containingexpensive Au. To match the final height of the bonding faces duringbonding (e.g., eutectic bonding), the bonding pads 97 are preferablyformed to be taller than the most protruded portion of the p- and n-sideelectrodes 92 and 80, namely, the height of the upper portion of thep-side finger electrode, by 1 to 3 μm. Accordingly, during the bondingoperation, excellent bonding results are obtained between thesemiconductor light emitting device and the mount part, and heatdissipation of the semiconductor light emitting device is facilitated.Here, the spacer layer 97 a and the bonding layer 97 b can be formed byvarious methods, such as plating, E-beam evaporation, thermalevaporation or the like.

Referring back to FIG. 14 and FIG. 15, all areas of the n-typesemiconductor layer 30, except the n-side contact area 31, arepreferably covered with the active layer 40 and the p-type semiconductorlayer 50. That is to say, for the semiconductor light emitting device100, the target etching area is limited to the n-side contact area 31,and there is no other area including the edges to be etched. Thoselateral faces around the semiconductor light emitting device 100 are allcut faces obtained by the scribing-and-braking process or the like. Assuch, the area of the active layer 40 generating light increases and thelight extraction efficiency is thus improved. Moreover, the step facesproduced from the etching process are minimized; namely, those stepfaces are limited to the exposed lateral faces of the active layer 40and the p-type semiconductor layer 50 that connect the top face of thep-type semiconductor layer 50 with the top face of the n-side contactarea 31. These exposed lateral faces of the active layer 40 and thep-type semiconductor layer 50 are the portions where it is hard, inparticular, to deposit the DBR 91 a constituting the non-conductivereflective film 91 during the formation of the non-conductive reflectivefilm 91. Consequently, the DBR 91 a on the exposed lateral faces of theactive layer 40 and the p-type semiconductor layer 50 may haverelatively lower reflection efficiency. By minimizing the exposedlateral faces of the active layer 40 and the p-type semiconductor layer50, it is possible to minimize areas having low reflection efficiency inthe DBR 91 a, thereby increasing the reflection efficiency as a whole.

FIG. 22 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,and FIG. 23 is a cross section view taken along line A-A′ of FIG. 22.The first feature of this embodiment is that finger electrodes 93 on thep-type semiconductor layer 50 are separated from each other, but aftereach electrical connection is set, they are then connected to each otherby an electrode 92. The electrode 92 serves to supply current to thosefinger electrodes 93, and is capable of reflecting light, dissipatingheat and/or connecting the device to outside. Although it is preferredthat the finger electrodes 93 are all separated, separating at least twofinger electrodes 93 can remove a branched part that connects thosefinger electrodes 93 with each other, thereby making it possible toreduce an unequal height on top of the device. The second feature ofthis embodiment is that the finger electrodes 93 are stretched out alongone lateral (C) direction of the device. For instance, in FIG. 22, theyare stretched out towards the electrode 80 from the electrode 92. Withthese long stretched finger electrodes 93, the device may be placedwithout leaning when it is overturned on a mount part (e.g., asub-mount, a package, or a COB (Chip on Board)). In this regard, it ispreferable to have the finger electrodes 93 as long as possible withinthe marginal space in the construction of a device. In this disclosure,as the finger electrodes 93 underlie the non-conductive reflective film91, they may be extended farther, past the electrode 80. The thirdfeature of this embodiment is that the electrode 80 is disposed abovethe non-conductive reflective film 91. The electrode 80 is connected toa finger electrode 81 through an electrical connection 82. The electrode80 has the same functions as the electrode 92. With such a construction,the side where the electrode 80 is placed has an increased height ascompared with FIG. 3, such that a height difference between the sides ofthe electrode 92 and the electrode 80 is reduced, being advantageous forcoupling the device with the mount part. This advantage becomes moreapparent especially when the eutectic bonding process is employed. Thefourth feature of this embodiment is that those finger electrodes 81 canbe arranged in a similar way as those finger electrodes 93. The fifthfeature of this embodiment is that an auxiliary heat-dissipating pad 97is provided. The auxiliary heat-dissipating pad 97 serves to dissipateheat from inside the device to outside and/or to reflect light, while italso electrically isolates the electrode 92 and/or the electrode 80,thereby preventing any electrical contact between the electrode 92 andthe electrode 80. Further, this auxiliary heat-dissipating pad 97 may beused for bonding. In particular, when the auxiliary heat-dissipating pad93 is electrically isolated from both the electrode 92 and the electrode80, even if it accidently comes into an electrical contact with eitherof the electrodes 92 and 80, the overall electrical operations of thedevice will not be affected thereby. A person skilled in the art wouldunderstand that all of the five features described above are notnecessarily required of this embodiment.

FIG. 24 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which auxiliary heat-dissipating pads 121, 122, 123 and 124 arepresent between the electrode 92 and the electrode 80. Preferably, theauxiliary heat-dissipating pads 121, 122, 123 and 124 are interposedbetween the finger electrodes 92, or between a finger electrode 92 and acorresponding finger electrode 81. Without the auxiliaryheat-dissipating pads 121, 122, 123 and 124 formed on the fingerelectrodes 92, the front face of the device and the mount part arebonded better during bonding (e.g. eutectic bonding), which is favorablein terms of heat dissipation of the device. The auxiliaryheat-dissipating pads 121 and 122 are separated from the electrodes 92and 80, while the auxiliary heat-dissipating pad 123 is connected to theelectrode 92 and the auxiliary heat-dissipating pad 124 is connected tothe electrode 80.

FIG. 25 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the finger electrode 93 is extended below the electrode 80(past the reference line B). By introducing the finger electrode 93 ontothe p-type semiconductor layer 50, a flip-chip is constructed in such away that current can be supplied without restrictions to the device areaneeded. There are two electrical connections 94's, which can be placedwherever necessary, according to the requirements for diffusing thecurrent. The electrical connection 94 on the left hand side may beomitted. The electrode 92 also serves as an auxiliary heat-dissipatingpad 97 (see FIG. 22). Even when the finger electrode 93 is notavailable, current can still be supplied by connecting the electricalconnection 94 directly to the light-transmitting conductive film 60, butcurrent cannot be supplied directly to the p-type semiconductor layer 50below the electrode 80. Introducing the finger electrode 93, however,enables to supply current even below the electrode 80 supplying currentto the n-type semiconductor layer 30. The same also applies to theelectrical connection 82.

FIG. 26 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the non-conductive reflective film 91 is made up of amulti-layer dielectric film 91 c, 91 d and 91 e. For example, thenon-conductive reflective film 91 can include a dielectric film 91 cmade of SiO₂, a dielectric film 91 d made of TiO₂, and a dielectric film91 e made of SiO₂, to serve as a reflective film. Preferably, thenon-conductive reflective film 91 is designed to include a DBRstructure. Considering that the manufacture of the semiconductor lightemitting device according to the present disclosure requires a structuresuch as finger electrodes 93 or finger electrodes 91, and a process forforming electrical connections 94 or electrical connections 82 evenafter the non-conductive reflective film 91 has been formed, extracaution should be given particularly for forming the dielectric film 91c made of SiO₂ as it can affect the reliability of the device (e.g.leakage current may occur) after the semiconductor light emitting deviceis finished. To this end, firstly, the dielectric film 91 c should havea thickness greater than those of the dielectric films 91 d and 91 ethat come after the dielectric film 91 c. Secondly, the dielectric film91 c needs to be prepared in a more appropriate way for ensuring thereliability of the device. By way of example, the dielectric film 91 cmade of SiO₂ can be obtained by CVD (Chemical Vapor Deposition), butmost of all (preferably) PECVD (Plasma Enhanced CVD); the repeating,laminated structure of dielectric film 91 d and the dielectric film 91 emade of TiO₂/SiO₂ DBR can be obtained by PVD (Physical VaporDeposition), but most of all (preferably) electron beam evaporation,sputtering or thermal evaporation, thereby ensuring the reliability ofthe semiconductor light emitting device according to the presentdisclosure as well as the performances as the non-conductive reflectivefilm 91. For step coverage, i.e. for the coverage of a mesa etched area,CVD is known to prevail over PVD, especially electron beam evaporation.

FIG. 27 is an enlarged view of the area where an electrical connectionis formed, which shows the light-transmitting conductive film 60, thefinger electrode 93 disposed on the light-transmitting conductive film60, the non-conductive reflective film 91 encompassing the fingerelectrode 93, the electrode 92, and the electrical connection 94connecting the finger electrode 93 with the electrode 92. In general, aplurality of metal layers is provided for forming electrodes, fingerelectrodes and bonding pads in the semiconductor light emitting device.The bottom layer should have an acceptable bonding strength with thelight-transmitting conductive film 60. It is mainly made of a materialsuch as Cr or Ti, but Ni, Ti, TiW or the like can also be used since itsmaterial is not particularly limited. In case of the top layer for wirebonding or for the connection with an external electrode, Au istypically used. Meanwhile, in order to reduce the amount of Au used andto complement a relatively low hardness of Au, it is possible to employ,between the bottom layer and the top layer, other materials such as Ni,Ti, TiW or W, depending on the specifications required, or Al or Ag,when a high reflectance is required. In the present disclosure, however,since the finger electrode 93 needs to be electrically connected to theelectrical connection 94, Au can be considered for use as the top layerfor finger electrode 93. Nevertheless, the inventors have learned thatit is not appropriate to use Au for the top layer for the fingerelectrode 93, because the Au gets easily peeled off due to a weakbonding strength between the Au and the non-conductive reflective film91 at the time of deposition of the non-conductive reflective film 91onto the Au top layer. To resolve this problem, the top layer of thefinger electrode can be formed of other materials such as Ni, Ti, W,TiW, Cr, Pd or Mo, in place of Au. In this way, the bonding strengthbetween the top layer and the non-conductive reflective film 91 to bedeposited on the top layer is retained and the reliability of the devicecan thus be improved. Further, those metals mentioned above are fullycapable of acting as a barrier during the formation of an opening in thenon-conductive reflective film 91 for the electrical connection 94,which can then be useful for ensuring the stability of the subsequentprocesses and the electrical connections.

FIG. 28 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,which further includes phosphors 220. The phosphor 220, in combinationwith an epoxy resin, forms an encapsulant 230. The semiconductor lightemitting device is placed at a reflective cup 210. The electrodes 80 and92 are electrically connected to outside, by means of a conductiveadhesive 240 and 250, respectively. The phosphor 220 can be coatedconformally, or can be applied directly, or can be disposed at a certaindistance away from the semiconductor light emitting device. The lightemitted from the active layer 40 is absorbed by the phosphor 220 andconverted to a light L1 of longer or shorter wavelength before travelingto outside, but part of the light L2 remains within the semiconductorlight emitting device or is reflected from the reflective cup 210 andthen returns into the semiconductor light emitting device where it isdestroyed, thereby impairing the efficiency of the semiconductor lightemitting device. In case that the non-conductive reflective film 91 hasa DBR 91-1, the reflection efficiency of the DBR 91-1 depends on thewavelength of the light. For instance, suppose that the light emittingfrom the active layer 40 is blue light having a wavelength of 450 nm,and that the DBR 91-1 is made of SiO₂/TiO₂ combination, where SiO₂ has arefractive index n₁ and TiO₂ has a wavelength of n₂, the thickness ofSiO₂ is adapted by 450 nm/4n₁, and the thickness of TiO₂ is adapted by450 nm/4n₂. However, when the phosphor 220 is a yellow phosphor (e.g.:YAG:Ce, (Sr,Ca,Ba)₂SiO₄:Eu), the phosphor 220 will have a wavelength of560 nm, and as a result thereof, the efficiency of the DBR 91-1 adaptedto the blue light will be substantially lowered. This problem can berelieved by introducing more DBRs 91-2 into the non-conductivereflective film 91, which are adapted to the wavelength of the phosphor220 present in the semiconductor light emitting device. In summary, theDBR 91-1 is designed based on λ_(Active)/4n₁, λ_(Active)/4n₂ (wherein,λ_(Active) is the wavelength of the active layer 40, and n₁ and n₂ arerefractive indexes of the DBR 91-1 materials), and the DBR 91-2 isdesigned based on λ_(Phosphor)/4n₁, λ_(Phosphor)/4n₂ (wherein,λ_(Phosphor) is the wavelength of the phosphor 220, and n₁ and n₂ arerefractive indexes of the DBR 91-2 materials). The expression “isdesigned based on” herein is not intended to mean that the DBR 91-1 musthave a thickness following this criteria. Rather, the DBR 91-1 may havea larger or smaller thickness than the reference thickness, when anoccasion arises. Nevertheless, such an occasion does not change the factthat the DBR 91-1 should be designed based on the λ_(Active)/4n₁,λ_(Active)/4n₂. When the phosphor 220 has several wavelengths of blue,green, orange, red and the like, additional DBR 91-2 may also be addedaccordingly. Needless to say, the material for the DBR 91-1 and thematerial for the DBR 91-2 may be partially or entirely different fromeach other. The DBR 91-1 and the DBR 91-2 comprising from 2 to 10periods can be ready for any desired wavelength. However, this does notnecessarily imply that any DBR comprising less or more periods cannotserve its performance.

FIG. 29 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,which further includes a DBR 91-3. This is the case where the phosphor220 includes two materials having different wavelengths. DBR 91-2 isdesigned based on λ_(Phosphor1)/4n₁, λ_(Phosphor1)/4n₂, and the DBR 91-3is designed based on λ_(Phosphor2)/4n₁, λ_(Phosphor2)/4n₂. Typically,when λ_(Phosphor1)> . . . >λ_(Phosphorn) (wherein n is a positiveinteger), arranging these DBRs in the non-conductive reflective film 91becomes an issue. Various arrangements can be possible, e.g., they canbe arranged from the p-type semiconductor layer 50 in order of longestwavelength to shortest, or vice versa. Also, more generally, it ispossible to design DBRs of several wavelength bands, taking the lightfrom the active layer 40 and/or the wavelength of the phosphor intoconsideration. If a DBR designed for a relatively shorter wavelength isarranged closer to the p-type semiconductor layer 50, the light of thisshorter wavelength may be farther from the finger electrode 93 and theelectrode 92, and thus, the absorption of the light by the fingerelectrode 93 and the electrode 92 is virtually prevented. Anotherpossible advantage is that if a DBR designed for a relatively longerwavelength is arranged closer to the p-type semiconductor layer 50, thereflectivity for the light which does not enter in a directionperpendicular to the DBR but enters at an angle with respect to the DBRwould be increased.

It is also possible to arrange a DBR designed for the shortestwavelength to be closest to or farthest from the p-type semiconductor 50and then put the other two DBRs to be intersected or mixed, or in anydiverse way if necessary.

The non-conductive reflective film 91 may become too thick if DBRs ofdifferent wavelengths are provided. Thus, if two materials of thephosphor 220 do not differ considerably in terms of the wavelength, itis also possible to design DBRs for those two materials. For example,DBRs can be designed based on ((λ_(Phosphor1)+λ_(Phosphor2))/2) /4n₁,((λ_(Phosphor1)+λ_(Phosphor2))/2)/4n₂. When the phosphor has wavelengthsof 550 nm, 580 nm, and 600 nm, a DBR can have the above design for 580nm and 600 nm because of a smaller difference in the wavelength.

Moreover, when the phosphor has wavelengths of 550 nm, 580 nm, and 600nm, a DBR can be designed for thicker wavelengths 580 nm and 600 nmtogether, which in turn enables to reduce the overall thickness of thenon-conductive reflective film 91.

Also, as described above, when one designs DBRs, DBRs can end up beingslightly longer than λ, that is, slightly thicker than the reference,instead of being adapted to the precise sizes of λ/4n₁, λ/4n₂. However,when such a DBR is introduced into a flip-chip, the thickness of thenon-conductive reflective film 91 may increase, and if applicable, itcan become difficult to form the electrical connection 94. To relievesuch problems, instead of increasing both thicknesses λ/4n₁ and λ/4n₂,only the thickness λ/4n₂ may be increased. Even if both thicknessesλ/4n₁ and λ/4n₂ are increased, it is still possible to make thethickness λ/4n₂ relatively larger. For instance, when blue light isemitted from the active layer 40, its wavelength is 450 nm. If the DBRis made of the SiO₂/TiO₂ combination, with SiO₂ having a refractiveindex of n₁ (=1.46) and TiO₂ having a wavelength of n₂ (=2.4), SiO₂ isadapted to have a thickness based on 450 nm/4n₁, and TiO₂ is adapted tohave a thickness based on 450 nm/4n₂. This is because the wavelength ischanged from 450 nm to 500 nm (in case of designing DBRs towards thelonger wavelengths), a larger refractive index results in a smallerchange in the thickness. While its effects on the improvement of thereflectivity is smaller than the case where both thicknesses are adaptedto 500 nm, it has other advantages that an increase in the thickness ofthe non-conductive reflective film 91 is relatively reduced, and thereflectivity is enhanced. This embodiment is applicable even when nophosphor 220 is introduced, as well as to the DBR 91-2 to which thephosphor 220 is introduced.

FIG. 30 graphically shows reflectivity as a function of wavelengths ofaluminum (Al), silver (Ag) and gold (Au). One can see that while thereflectivities of Al and Ag are acceptable at a lower wavelength band,the reflectivity of Au is even better at a wavelength band of 600 nm ormore. To apply this to the semiconductor light emitting devicesillustrated in FIG. 28 and FIG. 29, when the phosphor 220 includes a redphosphor, it is possible to treat the light having a shorter wavelengththan this by the non-conductive reflective film 91, and to reflect a redemission or a wavelength band of 600 nm or more using Au that isprovided to the bottom layer of a lower area of the electrode 92. Inaddition to this, it is also possible to provide a DBR, adapted to thered light, in the non-conductive reflective film 91. Further, Au may beincluded in the bottom layer or a lower area of the electrode 80, fingerelectrode 81 or finger electrode 93. The term “lower area” herein isintended to mean that other metal such as Cr or Ti that has a relativelybetter adhesive strength than Au can be added, in a very smallthickness, to the bottom layer, while still retaining the reflectiveperformance of Au. It should be understood that the technical ideaspresented in FIG. 28 to FIG. 30 are also applicable even if the fingerelectrodes 93 are not available, and that the present disclosure is notto be regarded simply as a combination of the number of featuressuggested in this disclosure. Needless to say, in addition to theelectrodes mentioned above, the auxiliary heat-dissipating pad 97illustrated in FIG. 22 and FIG. 24 as well as those auxiliaryheat-dissipating pads 121, 122, 123 and 124 can also be configured asdescribed above. The Au-containing electrode 92, auxiliaryheat-dissipating pad 97, auxiliary heat-dissipating pads 121, 122, 123and 124, finger electrode 93, electrode 80 and finger electrode 81 onthe opposite side of the p-type semiconductor layer 50 are referred toas reflective metal layers.

FIG. 31 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the semiconductor light emitting device includes a substrate10, a buffer layer 20 grown on the substrate 10, an n-type semiconductorlayer 30 grown on the buffer layer 20, an active layer 40 grown on then-type semiconductor layer 30, generating light via electron-holerecombination, and a p-type semiconductor layer 50 grown on the activelayer 40. The semiconductor light emitting device further includes alight-transmitting conductive film 60 formed on the p-type semiconductorlayer 50, a non-conductive reflective film 91 formed on thelight-transmitting conductive film 60 to reflect light from the activelayer 40 towards the substrate 10 used for growth or towards the n-typesemiconductor layer 30 if the substrate 10 has been removed, anelectrode 80 for providing electrons to the n-type semiconductor layer30, an electrode 92 for providing holes to the p-type semiconductorlayer 50, and a finger electrode 81 stretched into the n-typesemiconductor layer 30 and electrically connected to the electrode 80.Moreover, the semiconductor light emitting device further includes anelectrical connection 94 passing through the non-conductive reflectivefilm 91 to connect the electrode 92 and the light-transmittingconductive film 60, and another non-conductive reflective film 191interposed between the p-type semiconductor layer 50 and thelight-transmitting conductive film 60 below the electrical connection 94to reflect light from the active layer 40 towards to the n-typesemiconductor layer 30.

The non-conductive reflective film 91 can be formed on the exposedn-type semiconductor layer 30 after being etched and on a part of theelectrode 80.

The presence of the non-conductive reflective film 191 between thep-type semiconductor layer 50 and the light-transmitting conductive film60 below the electrical connection 94 prevents the non-conductivereflective film 91 from covering the electrical connection 94, such thatit is highly possible that the optical efficiency may not be decreased,but rather can be improved.

While serving as a reflective film, the non-conductive reflective film91 and the non-conductive reflective film 191 are preferably composed ofa light-transmitting material, for example, a light-transmittingdielectric material such as SiO_(x), TiO_(x), Ta₂O₅ or MgF₂, in order toavoid the absorption of light. When the non-conductive reflective film91 and the non-conductive reflective film 191 are composed of SiO_(x),their refractive indexes are lower than that of the p-type semiconductorlayer 50 (e.g., GaN) such that they can reflect part of the light havingan incidence angle greater than a critical angle towards thesemiconductor layers 30, 40 and 50. In addition, the non-conductivereflective film 91 and the non-conductive reflective film 191 can bemade up of a DBR. In such case, they are able to reflect a greateramount of light towards the semiconductor layers 30, 40 and 50.

The light-transmitting conductive film 60 serves to improve the currentdiffusion capacity, especially when the p-type semiconductor layer 50 iscomposed of GaN. As such, it can be made of a material such as ITO,Ni/Au or the like.

FIG. 32 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which a finger electrode 93 is stretched out between thenon-conductive reflective film 91 and the light-transmitting conductivefilm 60, for facilitating the supply of current (hole, to be moreaccurate) to the p-type semiconductor layer 50 from the electrode 92.The finger electrode 93 is electrically connected to the electrode 92,via the electrical connection 94 that passes through the non-conductivereflective film 91 in the vertical direction. Without the fingerelectrode 93, a number of electrical connections 94 will have to beformed to connect the electrode 92 directly to the light-transmittingconductive film 60 formed on almost the entire face of the p-typesemiconductor layer 50. In such case, however, it is not easy to obtainan acceptable electrical contact between the electrode 92 and thelight-transmitting conductive film 60, and problems may occur during themanufacturing process.

FIG. 33 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the non-conductive reflective film 191 is stretched out betweenthe light-transmitting conductive film 60 and the p-type semiconductorlayer 50 to the extent that it underlies the electrical connection 94 aswell as the finger electrode 93. With this long stretched non-conductivereflective film 191 until it underlies the finger electrode 93, it ispossible to prevent the absorption of light by the finger electrode 93and further to improve the optical efficiency.

FIG. 34 and FIG. 35 are views, each illustrating still another exampleof the semiconductor light emitting device according to the presentdisclosure, in which the non-conductive reflective film 19, unlike theone in the semiconductor light emitting device shown in FIG. 13, isformed up to a lateral face 11 of the substrate 10. As shown in FIG. 35,when the semiconductor light emitting device is mounted on a lead frameor on a PCB 2000, even if an opaque bonding material 111 mainly composedof a metal reaches the lateral face 11 of the substrate or the growthsubstrate 10, the non-conductive reflective film 91 is formed up to thelateral face 11 of the substrate 10, thereby making it possible toprevent the absorption of light by the bonding material 111. Thisconfiguration is not limited to the semiconductor light emitting deviceshown in FIG. 13, but it can be applied to any semiconductor lightemitting device using the non-conductive reflective film 91, includingthose semiconductor light emitting devices shown in FIG. 2 and FIG. 18.

FIG. 36 to FIG. 38 illustrate one example of a process for manufacturingthe semiconductor light emitting device shown in FIG. 34. First,referring to FIG. 36, the process prior to the formation of thenon-conductive reflective film 91 will be explained. A plurality ofsemiconductor layers 30, 40 and 50 are formed on the substrate 10, andthen an isolation process takes place to separate them into individualsemiconductor light emitting devices A and B. After that, thesesemiconductor light emitting devices are subjected to the conventionalsemiconductor manufacturing process, in order to produce an opticalabsorption barrier 95, a light-transmitting conductive film 50 andfinger electrodes 81 and 93. If necessary, the process for separatingthe semiconductor layers into individual semiconductor light emittingdevices A and B can be omitted. As will be described below, theisolation process itself can be a process for forming a groove 12 in thesubstrate 10. Moreover, if necessary, these semiconductor processes maybe carried out in different order.

Next, as shown in FIG. 37, a groove 12 is formed in the substrate 10 toexpose the lateral face 11 of the substrate 10. This process can beaccomplished by etching, sawing, laser scribing or the like. Forinstance, a groove 12 having a depth between 10 and 50 μm can be formed.

Next, as shown in FIG. 38, the non-conductive reflective film 91 isformed according to the method described above. If necessary, electricalconnections 82 and 94, electrodes 80 and 92, and an auxiliaryheat-dissipating pad 97 are formed. Afterwards, those individualsemiconductor light emitting devices A and B are separated into a shapeas shown in FIG. 34, by breaking, sawing or scribing-and-braking.

The process for forming the groove 12 may be performed immediately afterthe formation of the plurality of semiconductor layers 30, 40 and 50. Insuch case, an extra isolation process may be omitted. Therefore, theprocess for forming the groove 12 may be performed at any time as longas it falls prior to the formation of the non-conductive reflective film91.

FIG. 39 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which a plating film 112 may additionally be provided on theelectrodes 80 and 92 in order to prevent the bonding material 111 fromclimbing up to the semiconductor light emitting device. Preferably, theplating film has a height of 10 μm or more. More preferably, it has aheight of 20 μm or more. Such a height is not easily obtained bysputtering or electron-beam deposition commonly used for formingelectrodes 80 and 92. If the non-conductive reflective film 91 is formedon the lateral face of the growth substrate 10, the plating film 112 mayhave a lower height. The use of a metal like Ni enables to improve itsperformance as a diffusion barrier against the solder used in theeutectic bonding process. If the electrodes 80 and 92 are omitted, theplating film 112 can be formed by using electrical connections 82 and 94as seeds. The plating operation is accomplished by an electrolessplating process or an electroplating process.

FIG. 40 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the plating film 112 formed on the electrode 92 is larger thanthe plating film 112 formed on the electrode 80.

FIG. 41 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which a plating film 112 is applied to the semiconductor lightemitting device shown in FIG. 3, with the plating film 112 on theelectrode 80 being formed higher, thereby resolving the problem of aheight difference between the electrode 92 and the electrode 80 duringthe flip-chip bonding process. One plating process may suffice to matchthe height of the plating film 112 on the electrode 92 with the heightof the plating film 112 on the electrode 80, but, if necessary, theelectrode 92 and the electrode 80 may be plated separately.

FIG. 42 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which one single plating film 112 is applied to the semiconductorlight emitting device shown in FIG. 8. This plating film 112 may beformed across the entire electrode 92.

FIG. 43 is a view illustrating still another example of thesemiconductor light emitting device according to the present disclosure,in which the semiconductor light emitting device further includesphosphors 220. The phosphor 220, in combination with an epoxy resin,forms an encapsulant 230, and the semiconductor light emitting device isplaced at a reflective cup 210. The electrodes 80 and 92 areelectrically connected to outside, by means of a conductive adhesive 240and 250, respectively. The phosphor 220 can be coated conformally as inFIG. 18, or can be applied directly, or can be disposed at a certaindistance away from the semiconductor light emitting device. Unlike alateral chip in a junction-up form where a 50-180 μm thick substrate 50is usually disposed below thereof, the substrate 50 is disposed belowthe active layer 40 such that light generated in the active layer 40cannot be at the center of the reflective cup 210. This may lower theconversion efficiency of the phosphor 220, and the absorption of lightby the reflective cup 210 can also become a problem. However, thepresence of the plating film 112 shown in FIG. 39 to FIG. 42 can resolvethose problems. In this light, the plating film 112 preferably has athickness of 20 μm or more.

FIG. 44 is a view illustrating a relation among a dielectric film, a DBRand an electrode in the semiconductor light emitting device shown inFIG. 7, in which the dielectric film 91 b, the DBR 91 a and theelectrode 92 are deposited in order mentioned. Although a large portionof light generated in the active layer 40 (see FIG. 7, hereinafter) isreflected by the dielectric film 91 b and the DBR 91 a towards an n-sidesemiconductor layer 30, part of the light is trapped inside thedielectric film 91 b and the DBR 91 a, or emitted through the lateralfaces of the dielectric film 91 b and the DBR 91 b, or absorbed by theelectrode 92 made of a metal. The inventors analyzed the relation amongthe dielectric film 91 b, the DBR 91 a and the electrode 92, in view ofan optical waveguide. The optical waveguide is a structure that enclosesa propagation part of light by a material having a refractive indexlower than that of the propagation part of light and directs the lightby total reflection. In this regard, if the DBR 91 a can be taken as thepropagation part, the dielectric film 91 b can be taken as part of thestructure that encloses the propagation part. When the DBR 91 a iscomposed of SiO₂/TiO₂, with SiO₂ having a refractive index of 1.46 andTiO₂ having a refractive index of 2.4, the effective refractive index(which denotes an equivalent refractive index of light that can travelin a waveguide made of materials having different refractive indices,and has a value between 1.46 and 2.4) of the DBR 91 a is higher thanthat of the dielectric film 91 b composed of SiO₂. However, theelectrode 92 made of a metal presents on the opposite side, the lightabsorption may occur as the electrode 92 propagates the light in thelateral direction of the DBR 91 a.

FIG. 45 is a view illustrating a relation among a dielectric film havingan optical waveguide incorporated therein, a DBR and an electrode in thesemiconductor light emitting device shown in FIG. 7, in which thedielectric film 91 b, the DBR 91 a and the electrode 92 are deposited inorder mentioned, and a light-transmitting film 91 f having an effectiverefractive index lower than that of the DBR 91 a is interposed betweenthe DBR 91 a and the electrode 92. Preferably, the light-transmittingfilm 91 f has a thickness of at least λ/4n (here, λ denotes a wavelengthof light generated in the active layer 40, and n denotes a refractiveindex of the material forming the light-transmitting film 91 f). By wayof example, the light-transmitting film 91 f can be composed of adielectric such as SiO₂ having a refractive index of 1.46. When λ is 450nm (4500 Å), the light-transmitting film 91 f can be formed in athickness of 771 Å (4500/4×1.46=771 Å) or more. The use of such amaterial enables to increase the efficiency of an optical waveguide,considering that the efficiency of an optical waveguide increases as thedifference between the refractive index of the light-transmitting film91 f and the effective refractive index of the DBR 91 a increases. Thelight-transmitting film 91 f is not particularly limited as far as itseffective refractive index is lower than that of the DBR 91 a, and canbe made of a material, for example, metal oxide such as Al₂O₃; adielectric film such as SiO₂ or SiON; MgF; CaF or the like. However, ifthe difference between the refractive indices is small, thelight-transmitting film needs to be sufficiently thick to obtaincomparable effects. Besides, when the light-transmitting film is formedusing SiO₂, the efficiency of an optical waveguide can be increased byemploying SiO₂ having a refractive index lower than 1.46.

FIG. 46 is one example of the semiconductor light emitting device intowhich the optical waveguide described in FIG. 45 is incorporated. Here,a light-transmitting film 91 f having a refractive index lower than theeffective refractive index of a DBR 91 a is present on the DBR 91 a.That is to say, the non-conductive reflective film 91 further includesthe light-transmitting film 91 f. However, when the light-transmittingfilm 91 f is composed of a conductive material such as a metal oxide,the light-transmitting film 91 f does not always constitute part of thenon-conductive reflective film 91. It is possible to consider a casewhere the dielectric film 91 b is omitted. Although it is not desirablefrom the perspective of the optical waveguide, one should not exclude,from the perspective of the overall technical idea of this disclosure,the configuration including the DBR 91 a and the light-transmitting film91 f. The electrode 92 may be formed across the entirelight-transmitting film 91 f, or may be formed on only a part of thelight-transmitting film 91 f, or may be omitted.

FIG. 47 illustrates a conceptual view of the semiconductor lightemitting device to which an optical waveguide according to the presentdisclosure is applied. Here, the semiconductor light emitting deviceincludes an n-type semiconductor layer 30, an active layer 40, a p-typesemiconductor layer 50, a DBR 91 a provided on one side of the pluralityof semiconductor layers 30, 40 and 50, and two light-transmitting films91 f and 91 f having a refractive index lower than that of the DBR 91 adue to the presence of the DBR 91 a therebetween. The conductivity typesof the n-type semiconductor layer 30 and the p-type semiconductor layer50 may be reversed.

FIG. 48 is a view illustrating another example of the semiconductorlight emitting device to which an optical waveguide according to thepresent disclosure is applied. Here, a metal film 3000 is formed belowthe light-transmitting film 91 f. The metal film 3000 can serve simplyas a reflective film, or it can serve as an electrode as well. If themetal film 3000 serves as an electrode, an electrical connection 4000may be provided when needed, for supplying current to a plurality ofsemiconductor layers 30, 40 and 50.

FIG. 49 is a view illustrating another example of the semiconductorlight emitting device to which an optical waveguide according to thepresent disclosure is applied. As compared with the semiconductor lightemitting device shown in FIG. 48, a light-transmitting substrate orgrowth substrate 10 is provided between the n-type semiconductor 30 andthe light-transmitting film 91 f. An electrode 70 is formed on thep-type semiconductor layer 50, and an electrode 80 is formed on theexposed n-type semiconductor layer 30 by etching. The DBR 91 a reflectslight that is generated in the active layer 40 towards the opposite sideof the substrate 10 with respect to the active layer 40, that is,towards the p-type semiconductor layer 50, and forms an opticalwaveguide with the light-transmitting films 91 f and 91 f, emitting partof the light to the lateral face thereof.

FIG. 50 is a view illustrating still another example of thesemiconductor light emitting device to which an optical waveguideaccording to the present disclosure is applied. Here, alight-transmitting substrate 10 also serves as a light-transmitting film91 f. For instance, the substrate made of sapphire having a refractiveindex of about 1.8 and a thickness of 50 μm-180 μm can also serve as alight-transmitting film 91 f for the DBR 91 a composed of SiO₂/TiO₂.Here, the light-transmitting film 91 f underlying the DBR 91 a can bemade at the chip level, by depositing a dielectric material such asSiO₂, or a metal oxide. As such, it is possible to form thelight-transmitting film 91 f at the chip level in accordance with theproperties of the DBR 91 a, and to attach a reflective film 3000 to thelight-transmitting film 91 f at the chip level.

The following will now describe various embodiments of the presentdisclosure.

(1) A semiconductor light emitting device, characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination, wherein the plurality of semiconductorlayers are grown sequentially using a growth substrate; a firstelectrode for supplying either electrons or holes to the firstsemiconductor layer; a non-conductive reflective film formed on thesecond semiconductor layer, for reflecting light from the active layertowards the first semiconductor layer on the side of the growthsubstrate; and a finger electrode formed between the plurality ofsemiconductor layers and the non-conductive reflective film, which isextended to supply, to the second semiconductor layer, either electronsif holes are supplied by the first electrode or holes if the electronsare supplied by the first electrode, which is in electricalcommunication with the second semiconductor layer, and which has anelectrical connection for receiving either electrons or holes. It shouldbe noted that the electrical connection can have a specificconfiguration as in FIG. 3, and that the finger electrode 92 may createsuch an electrical connection if the finger electrode 92 comes into adirect contact with the electrode 93.

(2) The semiconductor light emitting device characterized in that thenon-conductive reflective film comprises a distributed bragg reflector.

(3) The semiconductor light emitting device characterized by furthercomprising: a second electrode connected to the electrical connection,for supplying, to the second semiconductor layer, either electrons ifholes are supplied by the first electrode or holes if the electrons aresupplied by the first electrode.

(4) The semiconductor light emitting device characterized in that theelectrical connection is formed, passing through the non-conductivereflective film from the second electrode to the finger electrode.

(5) The semiconductor light emitting device characterized by furthercomprising: an optical absorption barrier formed below the fingerelectrode and between the plurality of semiconductor layers and thefinger electrode, for preventing light generated from the active layerfrom being absorbed by the finger electrode.

(6) The semiconductor light emitting device characterized in that theoptical absorption barrier is composed of a light-transmitting materialhaving a refractive index lower than that of the second semiconductorlayer.

(7) The semiconductor light emitting device characterized in that theoptical absorption barrier is composed of a non-conductive material.

(8) The semiconductor light emitting device characterized in that theoptical absorption barrier is a light-transmitting dielectric filmhaving a refractive index lower than that of the second semiconductorlayer.

(9) The semiconductor light emitting device characterized by furthercomprising: a light-transmitting conductive film formed between thenon-conductive reflective layer and the second semiconductor layer, forelectrically communicating the finger electrode with the secondsemiconductor layer.

(10) The semiconductor light emitting device characterized in that thelight-transmitting conductive film covers the optical absorptionbarrier, and the finger electrode overlies the light-transmittingconductive film.

(11) The semiconductor light emitting device characterized in that thelight-transmitting conductive film has openings to enable thenon-conductive reflective film to come in contact with the plurality ofsemiconductor layers.

(12) The semiconductor light emitting device characterized in that thefinger electrode comes in contact with the optical absorption barrier.As shown in the example of FIG. 10, the light-transmitting conductivefilm is removed such that the finger electrode comes in direct contactwith the optical absorption barrier.

(13) The semiconductor light emitting device characterized in that thenon-conductive reflective film comprises a dielectric film underlyingthe distributed bragg reflector and having a refractive index lower thanthat of the second semiconductor layer.

(14) The semiconductor light emitting device characterized in that thesecond semiconductor layer is composed of a p-type group III nitridesemiconductor. The present disclosure is particularly suitable for agroup III nitride semiconductor known to have a poor current diffusioncapacity of the p-type GaN and to get assisted by a light-transmittingconductive film (e.g., ITO).

(15) The semiconductor light emitting device characterized in that thefinger electrode overlies the light-transmitting conductive film.

(16) The semiconductor light emitting device characterized in that thefirst electrode comprises a finger electrode which extends from thefirst electrode along the first semiconductor layer.

(17) A process for manufacturing a semiconductor light emitting device,characterized by comprising: preparing a plurality of semiconductorlayers that grows sequentially using a growth substrate, with theplurality of semiconductor layers including a first semiconductor layerhaving a first conductivity, a second semiconductor layer having asecond conductivity different from the first conductivity, and an activelayer interposed between the first semiconductor layer and the secondsemiconductor layer, generating light via electron-hole recombination;forming a finger electrode to enable electrical communication with thesecond semiconductor layer; forming, on the finger electrode, anon-conductive reflective film composed of a multi-layer dielectricfilm, for reflecting light from the active layer towards the firstsemiconductor layer on the growth substrate side, wherein thenon-conductive reflective film is formed such that a bottom layerobtained by chemical vapor deposition has a thickness greater than thethickness of each of two or more layers obtained by physical vapordeposition to be deposited on the bottom layer; and forming anelectrical connection, passing through the non-conductive reflectivefilm and being electrically connected to the finger electrode. Anexpanded scope of the manufacturing process according to the presentdisclosure, in which finger electrodes are omitted from thesemiconductor light emitting device.

(18) The process for manufacturing a semiconductor light emitting devicecharacterized in that the chemical vapor deposition is plasma enhancedchemical vapor deposition.

(19) The process for manufacturing a semiconductor light emitting devicecharacterized in that the physical vapor deposition is any one selectedfrom electron beam deposition and sputtering.

(20) The process for manufacturing a semiconductor light emitting devicecharacterized in that the bottom layer comprises SiO₂.

(21) The process for manufacturing a semiconductor light emitting devicecharacterized in that at least two layers comprise TiO₂.

(22) The process for manufacturing a semiconductor light emitting devicecharacterized in that at least two layers comprise a distributed braggreflector composed of SiO₂ and TiO₂.

(23) The process for manufacturing a semiconductor light emitting devicecharacterized by further comprising: forming, on the non-conductivereflective film, a metal layer to be connected with the electricalconnection. The metal layer can be either an electrode 92, or anauxiliary heat-dissipating pad 97 connected to the electrode 92.

(24) The process for manufacturing a semiconductor light emitting devicecharacterized by further comprising, prior to the step of forming anon-conducive reflective film, forming an electrode on the exposed,first semiconductor layer by etching.

(25) The process for manufacturing a semiconductor light emitting devicecharacterized in that, in the step of forming a finger electrode, thetop layer of the finger electrode is formed of a metal other than Au.

(26) The process for manufacturing a semiconductor light emitting devicecharacterized in that, in the step of forming a finger electrode, thetop layer of the finger electrode is formed of a metal selected from Ni,Ti, W, TiW, Cr, Pd and Mo.

(27) A semiconductor light emitting device, characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination; a first electrode supplying eitherelectrons or holes to the first semiconductor layer; a second electrodesupplying, to the second semiconductor layer, electrons if the holes aresupplied by the first electrode, or holes if the electrons are suppliedby the first electrode; and a non-conductive reflective film formed onthe second semiconductor layer, for reflecting light from the activelayer towards the first semiconductor layer on the side of the growthsubstrate, wherein the non-conductive reflective layer includes adistributed bragg reflector which comprises a first layer having a firstrefractive index (n₁) and a second layer having a second refractiveindex (n₂) greater than the first refractive index, with the first andsecond layers being laminated in an alternate manner, the second layerhaving a thickness designed for a longer wavelength than the wavelengthbased on which the first layer is designed. The first semiconductorlayer can have an n-type conductivity, and the second semiconductorlayer can have a p-type conductivity, and vice versa. The firstelectrode can have the same form as the electrode 80 in FIG. 3 and theelectrode 83 in FIG. 8. When the substrate 10 is removed, the firstelectrode can adopt a variety of forms that can be formed directly onthe first semiconductor layer. The second electrode can adopt a varietyof forms, in addition to the form of the electrode 92 in FIG. 3 and/orthe electrical connection 94.

(28) A semiconductor light emitting device, characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination; a light-transmitting conductive filmformed on the second semiconductor layer; a first non-conductivereflective film formed on the light-transmitting conductive film, forreflecting light from the active layer towards the first semiconductorlayer; a first electrode, which supplies either electrons or holes tothe plurality of semiconductor layers and is electrically connected tothe first semiconductor layer; a second electrode overlying the firstnon-conductive reflective film, which supplies, to the plurality ofsemiconductor layers, electrons if the holes are supplied by the firstelectrode, or holes if the electrons are supplied by the firstelectrode, and is electrically connected to the second semiconductorlayer; an electrical connection, passing through the firstnon-conductive reflective film and connecting the second electrode tothe light-transmitting conductive film; and a second non-conductivereflective film interposed between the second semiconductor layer andthe light-transmitting conductive film below the electrical connection,for reflecting light from the active layer towards the firstsemiconductor layer. The first semiconductor layer can have an n-typeconductivity, and the second semiconductor layer can have a p-typeconductivity, and vice versa. The first electrode can have the same formas the electrode 80 in FIG. 3 and the electrode 83 in FIG. 8. When thesubstrate 10 is removed, the first electrode can adopt a variety offorms that can be formed directly on the first semiconductor layer. Thesecond electrode can adopt a variety of forms, in addition to the formof the electrode 92 in FIG. 3 and/or the electrical connection 94.

(29) A semiconductor light emitting device, characterized by comprising:a growth substrate; a plurality of semiconductor layers that growssequentially on the growth substrate, with the plurality ofsemiconductor layers including a first semiconductor layer having afirst conductivity, a second semiconductor layer having a secondconductivity different from the first conductivity, and an active layerinterposed between the first semiconductor layer and the secondsemiconductor layer, generating light via electron-hole recombination; anon-conductive reflective film formed on the second semiconductor layerand extended up to a lateral face of the growth substrate, forreflecting light from the active layer towards the first semiconductorlayer on the side of the growth substrate; a first electrode supplyingeither electrons or holes to the plurality of semiconductor layers; anda second electrode supplying, to the plurality of semiconductor layers,electrons if the holes are supplied by the first electrode, or holes ifthe electrons are supplied by the first electrode.

(30) A semiconductor light emitting device, characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination; a non-conductive reflective film formedon the second semiconductor layer, for reflecting light from the activelayer towards the first semiconductor layer on the side of the growthsubstrate; a first electrode supplying either electrons or holes to theplurality of semiconductor layers; a second electrode supplying, to theplurality of semiconductor layers, electrons if the holes are suppliedby the first electrode, or holes if the electrons are supplied by thefirst electrode, wherein at least one of the first and second electrodesis provided on the opposite side of the plurality of semiconductorlayers with respect to the non-conductive reflective layer; and aplating film attached to the at least one of the first and secondelectrodes, wherein the plating film is provided on the opposite side ofthe plurality of semiconductor layers with respect to the non-conductivereflective layer.

(31) A semiconductor light emitting device, characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination; a first electrode supplying eitherelectrons or holes to the plurality of semiconductor layers; a secondelectrode supplying, to the plurality of semiconductor layers, electronsif the holes are supplied by the first electrode, or holes if theelectrons are supplied by the first electrode; a non-conductivereflective film, which is formed on the second semiconductor layer, forreflecting light from the active layer towards the first semiconductorlayer on the side of the growth substrate and includes a dielectric filmand a distributed bragg reflector in order mentioned from the secondsemiconductor layer; and a light-transmitting film formed on thedistributed bragg reflector as part of or separately from thenon-conductive reflective film, wherein the light-transmitting film hasa refractive index lower than an effective refractive index of thedistributed bragg reflector.

(32) A semiconductor light emitting device characterized by comprising:a plurality of semiconductor layers that grows sequentially on a growthsubstrate, with the plurality of semiconductor layers including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating alight with a first wavelength via electron-hole recombination; a firstelectrode, supplying either electrons or holes to the plurality ofsemiconductor layers; a non-conductive reflective film formed on thesecond semiconductor layer, reflecting the light from the active layer;a phosphor part provided over the first semiconductor layer on the sideof the growth substrate, converting the light of the first wavelengthgenerated in the active layer into a light of a second wavelength of 600nm or greater; and a reflective metal layer containing gold (Au) on aside facing the second semiconductor layer, wherein the reflective metallayer is provided on a side opposite to the phosphor part with respectto the plurality of semiconductor layers. The first semiconductor layercan have an n-type conductivity, and the second semiconductor layer canhave a p-type conductivity, and vice versa. The first electrode can havethe same form as the electrode 80 in FIG. 3 and the electrode 83 in FIG.8. When the substrate 10 is removed, the first electrode can adopt avariety of forms that can be formed directly on the first semiconductorlayer. The phosphor part can be a phosphor itself, or can adopt avariety of forms, such as a combined form of a phosphor and anencapsulating resin, or a conformally coated phosphor. It should benoted that a DBR can be designed based on light of a particular color.For instance, the expression “a yellow phosphor having a wavelength of560 nm” as used herein indicates a peak wavelength of the yellowphosphor. However, it will be apparent to a person skilled in the artthat the phosphor does not necessarily emit only the light having a peakwavelength of the yellow phosphor. Therefore, due to the limitation inlanguage skills in the description, the expression “designed based on aparticular wavelength” or “designed based on light of a particularcolor” as used herein is not to be construed as limiting, but to beunderstood that designing can be done to suit the properties of thatparticular yellow phosphor. In this way, although there may be argumentsfor the possibility of an unclear meaning of the expression, it would beobvious to a person skilled in the art that a DBR is designed based onlight emitted from the active layer, and that a DBR is designed based onlight converted by the phosphor.

According to one semiconductor light emitting device according to thepresent disclosure, it is possible to realize a new form of a reflectivefilm structure.

According to another semiconductor light emitting device according tothe present disclosure, it is possible to realize a new form of aflip-chip.

According to still another semiconductor light emitting device accordingto the present disclosure, it is possible to realize a reflective filmstructure that incorporates finger electrodes.

According to yet another semiconductor light emitting device accordingto the present disclosure, it is possible to embody a flip-chip thatincorporates a finger electrode.

What is claimed is:
 1. A semiconductor light emitting device,comprising: a plurality of semiconductor layers, including a firstsemiconductor layer having a first conductivity, a second semiconductorlayer having a second conductivity different from the firstconductivity, and an active layer interposed between the firstsemiconductor layer and the second semiconductor layer, generating lightvia electron-hole recombination; a first electrode, supplying eitherelectrons or holes to the plurality of semiconductor layers; a secondelectrode, supplying, to the plurality of semiconductor layers,electrons if the holes are supplied by the first electrode, or holes ifthe electrons are supplied by the first electrode; a non-conductivedistributed bragg reflector coupled to the plurality of semiconductorlayers, reflecting the light from the active layer; and a firstlight-transmitting film coupled to the distributed bragg reflector froma side opposite to the plurality of semiconductor layers with respect tothe non-conductive distributed bragg reflector, wherein the firstlight-transmitting film has a refractive index lower than an effectiverefractive index of the distributed bragg reflector.
 2. Thesemiconductor light emitting device as claimed in claim 1, furthercomprising: a second light-transmitting film interposed between theplurality of semiconductor layers and the distributed bragg reflector,coupled to the distributed bragg reflector.
 3. The semiconductor lightemitting device as claimed in claim 1, further comprising: a growthsubstrate interposed between the plurality of semiconductor layers andthe distributed bragg reflector, for growing the plurality ofsemiconductor layers thereon.
 4. The semiconductor light emitting deviceas claimed in claim 1, further comprising: a growth substrate interposedbetween the plurality of semiconductor layers and the distributed braggreflector, for growing the plurality of semiconductor layers thereon,wherein the growth substrate has a refractive index lower than aneffective refractive index of the distributed bragg reflector.
 5. Thesemiconductor light emitting device as claimed in claim 2, furthercomprising: a growth substrate interposed between the plurality ofsemiconductor layers and the distributed bragg reflector, for growingthe plurality of semiconductor layers thereon, wherein the growthsubstrate having a refractive index lower than an effective refractiveindex of the distributed bragg reflector, and wherein the growthsubstrate is the second light-transmitting layer.
 6. The semiconductorlight emitting device as claimed in claim 5, wherein the growthsubstrate is a sapphire substrate.
 7. The semiconductor light emittingdevice as claimed in claim 1, wherein the first light-transmitting filmhas a thickness of λ/4 or more, and wherein λ is a wavelength of lightgenerated in the active layer, and n is a refractive index of thelight-transmitting film.
 8. The semiconductor light emitting device asclaimed in claim 1, wherein the first light-transmitting film is a SiO₂film.
 9. The semiconductor light emitting device as claimed in claim 5,wherein the first light-transmitting film has a thickness of λ/4 ormore, and wherein λ is a wavelength of light generated in the activelayer, and n is a refractive index of the light-transmitting film. 10.The semiconductor light emitting device as claimed in claim 1, furthercomprising: a metal film coupled to the first light-transmitting film.11. A semiconductor light emitting device comprising: a plurality ofsemiconductor layers that grows sequentially on a growth substrate, withthe plurality of semiconductor layers including a first semiconductorlayer having a first conductivity, a second semiconductor layer having asecond conductivity different from the first conductivity, and an activelayer interposed between the first semiconductor layer and the secondsemiconductor layer, generating light via electron-hole recombination; afirst electrode supplying either electrons or holes to the plurality ofsemiconductor layers; a second electrode supplying, to the plurality ofsemiconductor layers, electrons if the holes are supplied by the firstelectrode, or holes if the electrons are supplied by the firstelectrode; a non-conductive reflective film, which is formed on thesecond semiconductor layer, for reflecting light from the active layertowards the first semiconductor layer on the side of the growthsubstrate and includes a dielectric film and a distributed braggreflector in order mentioned from the second semiconductor layer; and alight-transmitting film formed on the distributed bragg reflector aspart of or separately from the non-conductive reflective film, whereinthe light-transmitting film has a refractive index lower than aneffective refractive index of the distributed bragg reflector.
 12. Thesemiconductor light emitting device as claimed in claim 11, wherein thelight-transmitting film has a thickness of λ/4 or more, and wherein λ isa wavelength of light generated in the active layer, and n is arefractive index of the light-transmitting film.
 13. The semiconductorlight emitting device as claimed in claim 11, wherein thelight-transmitting film is composed of a dielectric material.
 14. Thesemiconductor light emitting device as claimed in claim 11, wherein thelight-transmitting film is composed of SiO₂.
 15. The semiconductor lightemitting device as claimed in claim 11, wherein the dielectric film andthe light-transmitting film are composed of a same material.
 16. Thesemiconductor light emitting device as claimed in claim 15, wherein thedielectric film has a refractive index lower than that of thelight-transmitting film.
 17. The semiconductor light emitting device asclaimed in claim 11, wherein the light-transmitting film is composed ofa metal oxide.
 18. The semiconductor light emitting device as claimed inclaim 11, further comprising: an electrical connection passing throughthe non-conductive reflective film and the light-transmitting film,thereby connecting the second semiconductor layer and the secondelectrode.
 19. The semiconductor light emitting device as claimed inclaim 11, wherein the second electrode is formed on thelight-transmitting film.
 20. The semiconductor light emitting device asclaimed in any one of claims 11 to 19, wherein the semiconductor is aGroup III nitride semiconductor.